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CHEMISTRYBOOKS - COMPANION CHEMISTRY

MOLE CONCEPT

N.C.E.R.T Exemplar

1. Two students performed the same experiment separately and each one of them recovered two readings

of mass which are given below. Correct reading of mass is 3.0 g. On the basis of given data, mark the

correct optioin out of the following statements.

A. Results of both the students are neither accurate nor precise

B. Results of student A are both precise and accurate

C. Results of student B are neither precise nor accurate

D. Results of student B are both precise and accurate

Answer: B

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2. A measured temperature on Fahrenheit scale is `200^(@)F`. What will this reading be on clesius scale?

A. `40^(@)C`

B. `94^(@)C`

C. `93.3^(@)C`

D. `30^(@)C`

Answer: C

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3. What will be the molarity of a solution which contains 5.85 g of NaCl (s) per 500 mL of the solution ?

A. `"4 mol L"^(-1)`

B. `"20 mol L"^(-1)`

C. `"0.2 mol L"^(-1)`

D. `"2 mol L"^(-1)`

Answer: C

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4. If 500 mL of a 5M solution is diluted to 1500 mL, what will be molarity of the solution obtained ?

A. 1.5 M

B. 1.66 M

C. 0.017 M

D. 1.59 M

Answer: B

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5. The number of atoms present in one mole of an element is equal to Avogadro number. Which of the

following elements contains the greatest number of atoms ?

A. 4 g He

B. 46 g Na

C. 0.40 g Ca

D. 12 g He

Answer: D

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6. If the concentration of glucose `(C_(6)H_(12)O_(6))` in blood is `0.9 "g L"^(-1)`, what will be the molarity

of glucose in blood ?

A. 5 M

B. 50 M

C. 0.005 M

D. 0.5 M

Answer: C

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7. What will be the molality of the solution containing 18.25 g of HCl gas in 500 g of water ?

A. 0.1 M

B. 1 M

C. 0.5 M

D. 1 m

Answer: D

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8. One mole of any substance contains `6.022 xx 10^(23)` atoms/molecules. Number of molecules of

`H_(2)SO_(4)` present in 100 mL of 0.02 M `H_(2)SO_(4)` solution is :

A. `12.044 xx 10^(20)` molecules

B. `6.022 xx 10^(23)` molecules

C. `1 xx 10^(23)` molecules

D. `12.044 xx 10^(23)` molecules.

Answer: A

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9. What is the mass percent of carbon in carbon dioxide ?

A. 0.00034

B. 27.27%

C. `3.4 %`

D. `28.7 %`

Answer: B

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10. The empirical formula and molecular mass of a compound are `CH_(2)O` and 180 g respectively. What

will be the molecular formula of the compound ?

A. `C_(9)H_(18)O_(9)`

B. `CH_(2)O`

C. `C_(6)H_(12)O_(6)`

D. `C_(2)H_(4)O_(2)`

Answer: C

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11. If the density of a solution is `3.12 "g mL"^(-1)`, the mass of 1.5 mL solution in significant figures is

A. 4.7 g

B. `4680 xx 10^(-3) g`

C. 4.680 g

D. 46.80 g

Answer: A

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12. Which of the following statements about a compound is incorrect?

A. A molecule of a compound may have atoms of different elements

B. A compound cannit be separated into its constituent elements by physical methods of separation

C. A compound retains the physical properties of its constituent elements.

D. The ratio of atoms of different elements in a compound is fixed

Answer: C

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13. Which of the following statements is correct about the reaction given below:-

`4Fe(s)+3O_(2)(g)rarr2Fe_(2)O_(3)(g)`

A. Total mass of iron and oxygen in reactants = total mass of iron and oxygen in products , therefore, it

follows law of conservations of mass

B. Total mass of reactants = total mass of products , therefore, law of multiple proportions is followed

C. Amount of `Fe_(2)O_(3)` can be increased by taking any one of the reactants (iron or oxygen) in

excess.

D. Amount of `Fe_(2)O_(3)` produced will decrease if the amount of any one of the reactants (iron or

oxygen) is taken in excess.

Answer: A

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14. Which of the following reactions is not correct according to the law of conservation of mass ?

A. `2Mg(s)+O_(2)(g)rarr2MgO(s)`

B. `C_(3)H_(8)(g)+O_(2)(g)rarrCO_(2)(g)+H_(2)O(g)`

C. `P_(4)(s)+5O_(2)(g)rarrP_(4)O_(10)(s)`

D. `CH_(4)(g)+2O_(2)(g)rarrCO_(2)(g)+2H_(2)O(g)`

Answer: B

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15. Which of the following statements indicates that law of multiple proportion is being followed?

A. Sample of carbon dioxide taken from any source will always have carbon and oxygen namely in the

ratio 1 : 2

B. Carbon forms two oxides namely `CO_(2) and CO`, where masses of oxygen which combine with

fixed mass of carbon are in the simple ratio 2 : 1

C. When magnesium burns in oxygen, the amount of magnesium taken for the reaction is equal to the

amount of magnesium in magnesium oxide formed

D. At constant temperature and pressure 200 mL of hydrogen will combine with 100 mL of oxygen to

produce 200 mL of water vapours.

Answer: B

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16. One mole of oxygen has at STP is equal to :

A. `6.022 xx 10^(23)` molecules of oxygen

B. `6.022 xx 10^(23)` atoms of oxygen

C. 16 g of oxygen

D. 32 g of oxygen

Answer: A::D

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17. Sulphuric acid reacts with sodium hydroxide as follows

`H_(2)SO_(4)+2NaOHrarrNa_(2)SO_(4)+2H_(2)O`

when 1L of 0.1M sulphuric acid solution is allowed to react with 1L of 0.1M sodium hydroxide solution, the

amount of sodium solphate formed and its molarity in the solution obtained is

A. `"0.1 mol L"^(-1)`

B. 7.10 g

C. `"0.025 mol L"^(-1)`

D. 3.55 g

Answer: B::C

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18. Which of the following pairs have the same number of atoms ?

A. 16 g of `O_(2)(g)` and 4 g of `H_(2)(g)`

B. 16 g of `O_(2)` and 44 g of `CO_(2)`

C. 28 g of `N_(2)` and 32 g of `O_(2)`

D. 12 g of C(s) and 23 g of Na(s)

Answer: C::D

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19. Which of the following solutions have the same molar concentration ?

A. 20 g of NaOH in 200 mL of solution

B. 0.5 mole of KCl in 200 mL of solution

C. 40 g of NaOH in 100 mL of solution

D. 20 g of KOH in 200 mL of solution

Answer: A::B

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20. 16 g of oxygen have same number of molecules as in :

A. 16 g of CO

B. 28 g of `N_(2)`

C. 14 g of `N_(2)`

D. 1.0 g of `H_(2)`

Answer: C::D

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21. Which of the following terms are unitless ?

A. Molality

B. Molarity

C. Mole fraction

D. Mass percent

Answer: C::D

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22. One of the statements of Dalton's atomic theory is given below "Compound are formed when atoms of

different element combine in a fixed ratio "

Which of the following laws is not related to this statement?

A. Law of conservation of mass

B. Law of definite proportions

C. Law of multiple proportions

D. Avogadro law

Answer: A::D

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23. Match the following

`{:("(i)","88 g of CO"_(2),"(a)","0.25 mol"),("(ii)",6.022 xx 10^(23)" molecules of "H_(2)O,"(b)","2 mol"),("

(iii)","5.6 litres of O"_(2)" at STP","(c)","1 mol"),("(iv)","96 g of O"_(2),"(d)",6.022xx10^(23)"molecules"),("

(v)","1 mole of any gas","(e)","3 mol"):}`

Answer: (i)-(b) ; (ii)-(c) ; (iii)-(a) ; (iv)-(e) ; (v)-(d) ;

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24. Match the following physical quantities with units

`{:(,"Phyrical quantity",,"Unit"),("(i)","Molarity","(a)","g mL"^(-1)),("(ii)","Mole fraction","(b)","mol"),("

(iii)","Mole","(c)","Pascal"),("(iv)","Molality","(d)","Unitless"),("(v)","Pressure","(e)","mol L"^(-1)),("

(vi)","Luminous intensity","(f)","Candela"),("(vi)","Density","(g)","mol kg"^(-1)),("(vii)","Density","

(h)","Nm"^(-1)),("(viii)","Mass","(i)","kg"):}`

Answer: (i)-(e) ; (ii)-(d) ; (iii)-(b) ; (iv)-(g) ; (v)-(c,h) ; (vi)-(f) ; (vii)-(a) ; (viii)-(i) ;

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25. Assertion (A) : The empirical mass of ethene is half of its molecular mass

Reason (R) : The empirical formula represents the simplest whole number ratio of various atoms present in

a compound.

A. Both A and R are true and R is the correct explanation of A

B. A is true but R is false

C. A is false but R is true

D. Both A and R are false

Answer: A

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26. Assertion(A) One atomic mass unit is defined as one twelth of the mass of one carbon-12 atom.

Reason(R) Carbon-12 isotope is the most abundant isotope of carbon and has been chosen as standard.

A. Both A and R are true and R is the correct explanation of A

B. Both A and R are true but R is not the correct explanation of A

C. A is true but R is false

D. Both A and R are false

Answer: B

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27. Assertion(A) Significant figures for 0.200 is 3 where as for 200 it is 1.

Reason(R) Zero at the end or right of a number are significatn provided they are not on the right side of the

decimal point.

A. Both A and R are true and R is the correct explanation of A

B. Both A and R are true but R is not the correct explanation of A

C. A is true but R is false

D. Both A and R are false

Answer: C

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Multiple choice

28. Assertion (A) : Combustion of 16 g of methane gives 18 g of water

Reason (R) : In the combustion of methane, water is one of the products.

A. Both A and R are true and R is the correct explanation of A

B. A is true but R is false

C. A is false but R is true

D. Both A and R are false

Answer: C

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1. In the experiement to verify the law of conservation of mass, weighing of the

A. reactants is only required

B. products is only required

C. reactants and the products is a must

D. contents are not essential

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2. The number of significant figures in 4.023 is :

A. 1

B. 2

C. 3

D. 4

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3. Number of significant figures in 0.050 is :

A. 1

B. 2

C. 3

D. 4

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4. Which one of the following will have the largest number of atoms?

(i) 1 g Au (s)

(ii) 1 g Na (s)

(iii) 1 g Li (s)

(iv) 1 g of Cl2(g)

A. 1g Au(s)

B. 1g Na(s)

Assignment

C. 1g Li(s)

D. `1g Cl_(2)(g)`

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5. Which of the following terms is independent of temperature ?

A. Normality

B. Molarity

C. Formality

D. Molality

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1. What is meant by precision in measurement ?

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2. How is accuracy in measurement different from precision ?

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3. Define significant figures.

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4. How many significant figures are there in :

(i) 94.046 and

(ii) 0.046 ?

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5. Which measurement is more precise, 0.4 g or 4.00 g ?

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6. Express the following upto four significant figures :

(i) 6.45372

(ii) 32.3928

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7. Which of the following have derived units ?

(i) Mass

(ii) Velocity

(iii) Temperature

(iv) Density

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8. What is conversion factor ?

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9. Convert 2.6 minutes into seconds ?

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10. Give the symbols of SI units of (i) Force (ii) Pressure

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11. The zeros between two non-zero digits are always significant. Give two examples to support it.

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12. What is the S.I unit of temperature ? How is this temperature related to celsius temperature ?

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Classification of matter

13. What is meant by inter conversion of units ? Give one example

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14. What are the different units of length ? Convert the same into S.I unit.

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15. What are derived SI units ? Derive the S.I units of (i) Density (ii) Acceleration (iii) Force (iv) Pressure

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1. What is the difference between solid and liquid states ?

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2. Name three most abundant elements in earth's crust

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3. Which of the following are metals ?

(i) Sodium

(ii) Sulphur

(iii) Phosphorus

(iv) Antimony

(v) Magnesium.

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4. Name a metal which is liquid at room temperature.

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5. Name the types of mixtures.

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6. What type of mixture is formed when iron filings and sulphur are mixed ?

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7. What is the nature of the following mixtures ?

(i) Air (ii) Petrol (iii) Gun powder

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Atomic, Molecular masses and Mole concept

8. Explain why is air sometime considered as a heterogeneous mixture.

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9. Define an element. What are the three type of elements ?

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10. Give on example each of the following mixtures

(i) Gas-Gas (ii) Gas-solid (iii) Liquid-Liquid

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11. Mixture of salt and water is a solution while that of oil and water is not. Explain.

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12. There is a definite number of elements while the number of compounds is not fixed, How will you

account for it ?

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1. Define mole.

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2. Define atomic mass of an element in terms of mole concept.

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3. What is the relation between the atomic mass and actual mass of one atom of an element ?

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4. Do one gram mole of sodium and calcium contain different number of atoms ?

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5. How much volume one mole of a gaseous substance occupy at N.T.P ?

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6. How many molecules of `CO_(2)` are present in its molar volume ?

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7. Under what conditions, do molar volumes of different gasees contain equal number of molecules ?

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8. Which has more number of atoms , 1g of hydrogen element of 1g of oxygen element ?

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9. `2.49 xx 10^(-18)g` of an element X contains `2.0 xx 10^(4)` atoms. What is the atomic mass of the

element X ?

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10. Explain gram atomic mass and gram molar mass of an element in terms of mole concept.

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11. Define molar mass. How will you calculate the molar mass of (i) `H_(2)SO_(4)` (ii) `Na_(2)CO_(3)` ?

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12. Explain gram molecular volume. How is it related to gram molecular mass ?

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Empirical molecular fromulae and chemical equations

1. Define the formula of a compound

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2. Define empirical formula of a compound.

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3. Give one example each of a molecule in which the empirical and molecular formulae are (a) same (b)

different.

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4. Out of empirical and molecular formulae, which represents the actual formula ?

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5. Name the law which requires the balancing of chemical equation.

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Problems for practice

6. What is the difference skeleton equation and balanced equation ?

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7. How will you indicate the evolution of a gas and the formation of a precipitate in a chemical equation ?

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8. Write the empirical formulae of the following compounds.

(i) `C_(6)H_(6)` (ii) `Na_(2)CO_(3)` (iii) `C_(6)H_(12)O_(6)` (iv) `H_(2)O_(2)` (v) `CH_(3)COOH` (vi)

`CuSO_(4)`

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1. Classify the following into metals and non-metals :

(i) Helium (ii) Sodium (iii) Hydrogen (iv) Mercury (v) Graphite (vi) Carbon (vii) Lead (viii) Magnesium (ix)

Chlorine (x) Phosphorus.

Answer: Metals : (ii),(iv),(viii) ; Non-metals : (i),(iii),(v),(vi) ,(ix),(x)

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2. Why is a mixture of salt in water a solution while that of oil water is not ?

Answer: Salt and water form homogeneous mixture (solution). Oil and water constitue

heterogeneous mixture (not a solution)

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3. Classify the following into elements, compounds and mixtures

(i) Marble (ii) Honey (iii) Touch paste (iv) Sugar (v) Gold (vi) Brass (vii) Nitre (viii) Slakes lime (ix) Nitrogen

(x) Fruit juice.

Answer: Elements : (v), (ix) ; Compounds : (i), (iv),(vii),(viii) ; Mixture : (ii),(iii) ; (vi) ; (x)

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4. Give the names of two elements which act as metalloids.

Answer: Arsenic (As), Antimony (Sb)

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5. When two substances A and B are powdered together in a pestle and mortar, a larger amount of heat is

given out and a substance C is formed. The properties of C are found to be different from those of A and B.

It is substance C an element, compound or mixture ?

Answer: C' is compound

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6. Name a mixture used : (i) by all living beings (ii) in te construction for building materials (iii) as a food.

Answer: (i) Air (ii) Cement (iii) Milk

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7. When sulphuric acid is added carefully to water, what is formedm a compound or mixture ?

Answer: Mixture

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8. Why is air sometimes regarded as heterogeneous mixture ?

Answer: Since dust particles are present

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9. How many milligrams of bromine are present in a bottle containing 1/10 kg ?

Answer: `10^(5)` mg

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10. Light waves travel with the speed of `3 xx 10^(8) "m s"^(-1)`. Express the speed in miles are per hour.

Answer: `6.75 xx 10^(8) "miles/hr"`

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11. An object travels with the speed of 96 miles per hour. Calculate the speed of the object in SI units.

Answer: `42.7 ms^(-1)`

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12. Calculate the speed of a train `ms^(-1)` which covers 972 miles in 27 hours (1 mile = 1.60 km)

Answer: `16.0 ms^(-1)`

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13. Convert 40 calories into joules.

Answer: 167.36 J

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14. What do the following abbreviations stand for ?

(i) dL (ii) dm (iii) `mu m` (d) nL

Answer: (a) decilitre (b) decimetre (c) micrometre (d) nanolitre

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15. What are the S.I prefix corresponding to following multipliers ?

(a) `10^(-6)` (b) `10^(9)` (c) `10^(-12)` (d) `10^(-2)`

Answer: (a) micro (b) giga (c) pico (d) centi

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16. What units do the following abbreviations represent ?

(a) `mug` (b) dm (c) ps (d) kA (e) m mol ?

Answer: (a) mixrogram (b) decimetre (c) pico second (d) kiloampere (e) milli mol

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17. Which of the following has maximum number of significant figures ?

(i) 0.00453 (ii) 4.8046 (iii) 5.643

Answer: 4.8046 (Five)

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18. What is the correct reading of a device with precision 1/100 of a unit ?

(i) 3.600 g (ii) 3.60 g (iii) 3.6 g

Answer: 3.60 g

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19. State the number of significant figures in each o the following :

(i) `2.65 xx 10^(5)` (ii) 0.00544 (iii) 0.368 (iv) 0.020

Answer: (i) Three (ii) Three (iii) Three (iv) Two

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20. Write the following numbers in exponential notation

(i) 4250000 (ii) 0.0008432

Answer: (i) `4.25 xx 10^(6)` (ii) `8.432 xx 10^(-4)`

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21. What is the number of significant figures in each of the following measurement ?

(a) 4.425 g (b) `5.6 xx 10^(3)` cm (c) `"0.000124 m"^(3)`

Answer: (a) Four (b) Two (c) Three

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22. Add : (i) `93.4 + 4.03` (ii) `77.86, 14.12 and 5.7`

Answer: (i) 97.4 (ii) 97.7

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23. Subtract : (i) 0.015 from 5.16 (ii) 16.92 from 237.5 (iii) 0.0604 from 0.08638

Answer: (i) 5.14 (ii) 220.6 (iii) 0.0260

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24. Multiply : (i) `730 xx 240` (ii) `5.02 xx 10^(23) xx 1.0064` (iii)`0.06204 xx 296.4`

Answer: (i) `1.752 xx 10^(5)` (ii) `5.05 xx 10^(23)` (iii) 18.4

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25. Express the following upto four significant figures

(i) 6.5089 (ii) 32.3928 (iii) `8.721 xx 10^(4)` (iv) 2000

Answer: (i) 6.509 (ii) 32.39 (iii) `8.721 xx 10^(4)` (iv) `2.000 xx 10^(3)`

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26. `"9.84 cm"^(3)` of ethyl alcohol is withdrawn from a flask containing `"45.3 cm"^(3)` of the sample. What

is the volume ethyl alcohol left in the flask ?

Answer: `35.4 cm^(3)`

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27. What is the volime of a piece of silver which weighs 21.5639 g. The density of silver is `10.4 g//cm^(3)` ?

Answer: `2.07 cm^(3)`

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28. Report the area of a rectangle to approprite number of significant figures. Given that the edge lengths of

the rectangle are 6.221 cm and 5.2 cm.

Answer: `32.4 cm^(3)`

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29. When 6.3 g of `NaHCO_(3)` (sodium bicarbonate) is added to a solution of `CH_(3)COOH` (acetic acid)

weighing 15 g, it is observed that `3.3 g CO_(2)` is released to the atmosphere. The residue is found to

weigh 18.0 g. Show that the data is in agreement with the law of conservation of mass.

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30. 1.7 g of `AgNO_(3)` dissolved in 100 g of water wire mixed with 0.585 g of NaCl dissolved in 100 g of

water when 1.435 g of AgCl and 0.85 g of `NaNO_(3)` were formed. Justify that the data illustrates law of

conservation of mass.

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31. 4.9 g of `KClO_(3)` when heated produced 1.92 g of oxygen and the residue of KCl left was found to

weigh 2.96 g. Show that the data illustrates the law of conservation of mass.

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32. Silver chloride was prepared in two ways :

(i) 0.5 g of a silver wire was dissolved in concentrated nitric acid and the excess of hydrochloric acid was

added to it. The precipitate of silver chloride was separated by filtration, washed, dried and then weighed.

The weight of the residue was found to be 0.66 g

(ii) In another experiement, 1g of silver metal was heated in a current of chlorine till it was completely

converted into its chloride which was found to weight 1.32 g

Show that the data is according to the Law of Constant composition.

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33. If law of constant composition is true, what weights of calcium, carbon and oxygen are present in 1.5 g

of calcium carbonate ? Given that the sample of calcium carbonate from another sample contains Ca = 40.0

%, C = 12.0 % and O = 48.0 %

Answer: Wt. of Ca = 0.6 g ; C = 0.18 g ; O = 0.72 g

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34. 0.79 g of iron unite directly with 0.4 g sulphur to form ferrous sulphate. If 2.8 g of iron are dissolved in

dilute HCl and excess of sodium sulphide solution is added, 4.4 g iron sulphite is precipitated. Show that the

data is according to Law of constant composition.

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35. Show that the data given below is in agreement with the law of constant composition

`{:("Exp. No.","Mass of iron","Mass of iron oxide"),("(i)","2.7812 g","3.9756 g"),("(ii)","3.0499 g","4.3596 g"),("

(iii)","4.4913 g","6.4202 g"):}`

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36. 10 mL of `H_(2)` combine with 5 mL of `O_(2)` to form `H_(2)O` when 200 mL of `H_(2)` at S.T.P. is

passed through heated CuO, latter loses 0.144 g of its weight. Does the above data correspond to the law of

constant composition ?

Answer: Yes

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37. Hydrogen peroxide and water contain 5.93 % and 11.2 % of hydrogen respectively. Show that the data

illustrates the law of multiple proportions.

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38. The following data were obtained for three oxides of lead

(i) 1.77 g of red oxide contains 1.61 g of lead

(ii) 6.90 g of the yellow oxide contains 6.42 g of lead

(iii) 1.195 g of brown oxide contains 1.035 of lead.

Justify that the data is in agreement with the law of multiple proportions.

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39. 0.14 g of an element A combines with 0.16 g of the elements B. Also 0.05 g of another element C

combines with 0.35 g of A. It was also found that 0.2857 g of C combines with 2.2857 g of B. Show that the

data illutrates the law of reciprocal proportions.

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40. Verify the law of reciprocal proportions from the following data :

KCl contains 52.0 % potassium , KI contains 23.6 % potassium while Icl contains 78.2 % iodine.

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41. Boron occurs in nature in the form of two isotopes having atomic masses 10 and 11. What are the

percentage abundances of these isotopes in a simple a boron having average atomic mass of 10.8 ?

Answer: `B - 10 = 20,B - 11= 80`

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42. A sample of oxygen consists of three isotopes O - 16, O - 17 and O - 18 in the relative abundance of

99.76 %, 0.04 % and 0.20 % respectively. What is the average atomic mass of oxygen ?

Answer: 16.004 u

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43. Calculate the mass of :

(i) 1.2 gram atom of oxygen (ii) 5.2 gram atom of iodine

(iii) 5.6 gram atom of chlorine.

Answer: (i) 19.2 g (ii) 660.4 g (iii) 198.8 g

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44. Which has the maximum and minimum mass ?

(A) 25.6 g of oxygen (atomic mass = 16)

(B) 2.56 gram atom of sodium (atomic mass = 23)

(C) 0.256 gram molecule of water (molecular mass = 18)

(D) 0.256 gram atom of iodine (atomis mass = 127)

Answer: Maximum mass = B, Minimum mass Cl

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45. Calculate the number of moles of iron in a simple containing `1.0 xx 10^(22)` atoms.

Answer: 0.0166 mol

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46. How many molecules and atoms of phosphorus are present in 0.1 mole of `P_(4)` molecules ?

Answer: `6.022 xx 10^(22)` molecules (ii) `2.409 xx 10^(23)` atoms

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47. Calculate the number of atoms of hydrogen, oxygen and sulphur in 0.2 mole of sulphuric acid

`(H_(2)SO_(4))`

Answer: `H = 2.409 xx 10^(23) ; O = 4.818 xx 10^(23) ; S = 1.204 xx 10^(23)`

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48. How many atoms of fluorine are present in `1.9 xx 10^(-6)` gram of fluorine ? The atomic mass of

fluroine is 19 amu.

Answer: `6.022 xx 10^(16)` atoms

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49. How many atoms of each constituent element are present in 50 g of `CaCO_(3)` ?

Answer: (i) `Ca = 3.01 xx 10^(23)` (ii) `C = 3.01 xx 10^(23)` (iii) `O = 9.03 xx 10^(23)`

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50. How many molecules of water are present in 0.9 g of water ?

Answer: `3.01 xx 10^(22)` molecules

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51. Calculate the number of molecules in a drop of water weighing 0.05 g.

Answer: `1.672 xx 10^(21)` molecules

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52. Calculate the number of molecules present in 34.2 g of can sugar `[C_(12)H_(22)O_(11)]`.

Answer: `6.022 xx 10^(22)` molecules

View Text Solution

View Text Solution

53. Haemoglobin contains 0.25 % iron by mass. The molecular mass of haemoglobin is 89600. Calculate

the number of iron atoms per molecule of haemoglobin.

Answer: 4

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54. How many moles of gold are present in `49.25 g` of gold rod ? (Atomic mass of gold = 197)

Answer: 0.25 mol

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55. 16.26 milligram of sample of an element X contains `1.66 xx 10^(20)` atoms. What is the atomic mass of

the element X ?

Answer: 59 g

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56. Calculate the mass of the following :

(i) 1 atom of carbon (ii) 1 atom of silver (iii) 1 molecule 1 benzene `(C_(6)H_(6))`

(iv) 1 molecule of water `(H_(2)O)`

Answer: (i) `1.99 xx 10^(-23)g` (ii) `1.79 xx 10^(-22) g` (iii) `1.295 xx 10^(22) g` (iv) `2.99 xx 10^(-23) g`

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57. One million of silver atoms weigh `1.79 xx 10^(-16)g`. Calculate the atomic mass of silver.

Answer: 107.8 u

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58. Calculate the number atoms of oxygen present in 88 g of `CO_(2)` ? What would be the weight of CO

having the same number of oxygen atoms ?

View Text Solution

59. Which of the following has the maximum mass

(a) 20 g of phosphorus

(b) 5 moles of water

(c) `12 xx 10^(24)` atoms of hydrogen ?

Answer: 5 moles of water

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60. Suppose a chemist has chosen `10^(20)` as the number of particles in a mole. What would be the

molecular mass of oxygen gas ?

Answer: `5.31 xx 10^(-3) g`

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61. Calculate the weight of carbon of monoxide having the same number of oxygen atoms as are present in

88 g of carbon dioxide.

View Text Solution

62. What is the mass in grams of : (i) `6.022 xx 10^(23)` atoms of oxygen

(ii) `1.0 xx 10^(23)` molecules of `H_(2)S`

(iii) `6.022 xx 10^(23)` molecules of oxygen ?

Answer: (i) 16 g (ii) 5.645 g (iii) 32 g

View Text Solution

63. A chemist wishes to prepare `6.022 xx 10^(24)` molecules of sulphur dioxide. How many gram-atoms of

sulphur does the need ?

Answer: 10 gram atoms

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64. Which of the following has maximum mass ?

(i) 0.1 mole of `KNO_(3)`

(ii) `1 xx 10^(23)` molecules of `CH_(4)`

(iii) `112 cm^(3)` of hydrogen at S.T.P ?

Answer: 0.1 mole of of `KNO_(3)` has maximum mass of 10.1 g

View Text Solution

65. What is the mass of carbon present in 0.5 moles of `K_(4)[Fe(CN)_(6)]` ?

Answer: 36 g

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66. What is the mass of one molecule of yellow phosphorus in milligrams ? (Atomic mass of P = 30)

Answer: `1.993 xx 10^(-19) mg`

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67. Calculate the number of molecules and number of atoms present in 11.2 litres of oxygen `(O_(2))` at

N.T.P

Answer: `3.01 xx 10^(23)` molecules, `6.02 xx 10^(23)` atoms.

View Text Solution

68. Calculate the volume at N.T.P occupied by

(i) 14 g of nitrogen

(ii) 1.5 gram moles of carbon dioxide

(iii) `10^(21)` molecules of oxygen.

Answer: (i) 11.2 L (ii) 33.6 L (iii) `37.2 cm^(3)`

View Text Solution

69. Calculate the number of molecules present in (a) 1 kg oxygen (b) `1 dm^(3)` of hydrogen at N.T.P

Answer: (a) `1.88 xx 10^(25)` (b) `2.69 xx 10^(22)`

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70. 1.7 g of an unknown gas occupies 2.24 L at N.T.P Calculate its molecular mass. Identify the gas.

Answer: 17 g, Ammonia

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71. 16 g of an ideal gas `SO_(X)` occupies 5.6 L at S.T.P. What is its molecular mass ? What is the value of

X ?

Answer: `x = 2, SO_(2)`

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72. Determine the precentage of water of crystallisation in pure sample of green vitriol

`(FeSO_(4).7H_(2)O)`

Answer: 0.4532

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73. It was found that 16.5 g of a metal combine with oxygen to form 35.6 g of metal oxide. Calculate the

percentage of metal and oxygen in the compound.

Answer: Metal = 46.3 %, Oxygen = 53.7 %

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74. Hydrogen and oxygen are combined in the ratio of 1 : 16 by mass in hydrogen peroxide. What is the

percentage compostion of hydrogen peroxide ?

Answer: Oxygen = 94.15 %, Hydrogen = 5.88 %

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75. Calculate the percentage composition of potassium hydrogen sulphate `(KHSO_(4))`

Answer: `K = 28.68 %, H=0.735 %, S = 23.53 %, O 47.06 %

View Text Solution

76. What is the percentage of water of crystallisation in a pure sample of washing soda `(Na_(2)CO_(3).10

H_(2)O)` ?

Answer: 0.6294

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77. The hydrated salt `Na_(2)CO_(3)x H_(2)O` undergoes 63 % loss in mass on heating and becomes

anhydrous. What is the value of x ?

Answer: 10

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78. The atomic mass of a metal M is 56. Calculate the empirical formula of its oxide containing 70 % metal.

Answer: `M_(2)O_(3)`

View Text Solution

79. An organic compound was found to contain the following consitituents : C = 33 % , H = 4.7 % , N = 13.2

%, Cl = 33.4 %. Determine the empirical formula of the compound

Hint : Calculate the percentage of oxygen since the sum of the percentages of elements is not 100. The

percentage of oxygen = 15.7.

Answer: `C_(3)H_(5)NClO`

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80. An organometallic compound on analysis gave the following results : `C = 64.4 %, H = 5.5 %, Fe = 29.9

%`. Determine the empirical formula.

Answer: `C_(10)H_(10)Fe`

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81. A Cylinder contains 0.32 g of oxygen. The same volume of an unknown gas 'X' under similar conditions

of temperature and pressure weighs 0.26 g. The gas 'X' is known the contain only carbon and hydrogen

atoms in the ratio 1 : 1. Identify the gas 'X'.

Answer: `C_(2)H_(2)`

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82. Four grams of copper chloride on analysis was found to contain 1.890 g of copper and 2.110 g of

chlorine (Cl). What is the empirical formula of copper chloride ?

Answer: `CuCl_(2)`

View Text Solution

83. What is the empirical formula of Kaolin the percentage composition of which is as under :

`Al_(2)O_(3) = 39.5 %, SiO_(2)=46.6 %,H_(2)O=13.9 %`

(Atomic masses : `Al = 27, Si= 28,O = 16,H=1`)

Hint : Radical mass of `Al_(2)O_(3) = 102,SiO_(2) = 60,H_(2)O=18`.

Answer: `Al_(2)O_(3).2SiO_(2).2H_(2)O`

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84. The molecular mass of benzene is 78 amu. Its percentage composition is 92.31 % C and 7.69 % H.

Determine the molecular formula of benzene.

Answer: `C_(6)H_(6)`

View Text Solution

View Text Solution

85. An organic compound on analysis gave the following percentage composition :

`C = 57.8 %, H= 3.6 %` and the rest is oxygen. The vapour density of the compound was found to be 83.

Find the molecular formula of the compound.

Answer: `C_(8)H_(6)O_(4)`

View Text Solution

86. A compound of C, H and N contains the three element in the ratio of `9 : 1 : 3.5`. Calculate the molecular

formula given that the molecular mass of the compound is 108 amu

Hint : Percentgae of `C=(9)/(13.5)xx100=66.7,H=(1)/(13.5)xx100=7.4,N=(3.5)/(13.5)xx100=25.9`.

Answer: `C_(6)H_(8)N_(2)`

View Text Solution

87. 0.45 g of an organic compound gave 0.44 g of `CO_(2)` and 0.09 g of `H_(2)O`. The molecular mass of

the compound is 90 amu. Calculate the molecular formula.

Answer: `C_(2)H_(2)O_(4)`

View Text Solution

88. A crystalline salt on being rendered anhydrous loses 45.6 % of its weight. The percentage composition

of anhydrous salt is : `Al = 10.5 % , K = 15.1 % , S = 24.96 %, O = 49.92 %`

Find the simplest formula of the anhydrous and crystalline salt.

Answer: Anhydrous salt : `Kal_(2)S_(2)O_(8)` ; Hydrated salt : `KAlS_(2)O_(8).12H_(2)O`

View Text Solution

89. Determine the molecular formula of the compound which contains `H = 6.67 %, C = 40 %` and the rest

is oxygen. 0.6 g of the compound occupy 224 cc at N.T.P

Answer: `C_(2)H_(4)O_(2)`

View Text Solution

90. Compound 'A' is found to contain `36.5 % Na,25.4 % S and 38.1 % O`. Its molecular mass is 126.

Calculate the molecular formula of the compound. The compound 'A' is easily oxidised to another compound

'B'. Calculate the percentage composition of 'B'.

Answer: `A = Na_(2)SO_(3),B=Na_(2)SO_(4)` ; In `'B' ; Na = 32.4 % ; S = 22.54 % and O = 45.07 %`

View Text Solution

91. In a compound, C, H and N are present in the ratio `9 : 1: 3.5` by weight. If the molecular weight. If the

molecular weight of the compound is 108, what is the number of hydrogen atoms present in the molecular

formula of the compound ?

Answer: `=8`

View Text Solution

92. Balance the following chemical equations by hit and trial method

`{:((a),Ca+H_(2)OrarrCa(OH)_(2)+H_(2)),("(b),Al_(4)+H_(2)OrarrAl(OH)_(3)+CH_(4)),

((c),H_(3)PO_(3)rarrH_(3)PO_(4)+PH_(3)),((d),KMnO_(4)+HClrarrKCl+MnCl_(2)+H_(2)O+Cl_(2)),

((e),K_(2)Cr_(2)O_(7)+H_(2)SO_(4)rarrK_(2)SO_(4)+Cr_(2)(SO_(4))_(3)+H_(2)O+O_(2)):}`

Answer: `{:((a),Ca+2H_(2)OrarrCa(OH)_(2)+H_(2)),((b),Al_(4)C_(3)+12H_(2)Orarr4Al(OH)_(3)+3CH_(4)),

((c),4H_(3)PO_(3)rarr3H_(3)PO_(4)+PH_(3)),

((d),2KMnO_(4)+16HClrarr2KCl+2MnCl_(2)+8H_(2)O+5Cl_(2)),

((e),2K_(2)Cr_(2)O_(7)+8H_(2)SO_(4)rarr2K_(2)SO_(4)+2Cr_(2)(SO_(4))_(3)+8H_(2)O+3O_(2)):}`

View Text Solution

93. Balance the following chemical equations by partial method indicating the partial equations involved

`{:((a),H_(2)S+HNO_(3)rarrNO+H_(2)O+S),((b),Cu+H_(2)SO_(4)rarrCuSO_(4)+SO_(2)+H_(2)O),

((c),C+H_(2)SO_(4)rarrCO_(2)+SO_(2)+H_(2)O),((d),I(2)+HNO_(3)rarrHIO_(3)+NO_(2)+H_(2)O):}`

Answer: `(##SKM_COMP_CHM_V01_XI_C01_E01_260_A01##)`

View Text Solution

94. Calculate the weight of iron which will be converted into its oxide `(Fe_(3)O_(4))` by the action 18 g of

steam on it.

Answer: 42 g

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95. Calculate the quantity of slaked lime `Ca(OH)_(2)` required to soften 6000 litres of well water containing

16.2 g of calcium bicarbonate per 100 litres.

Answer: 4440 g

View Text Solution

96. A mineral haematite `(Fe_(2)O_(3))` contains unwanted material called gangue in addition to

`Fe_(2)O_(3)`. If 5 kg of the ore contains 2.78 kg of iron, what is the percentage purity of `Fe_(2)O_(3)` ?

Answer: 0.7943

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97. What weight of zinc would be required to produce enough hydrogen by reacting with dilute HCl to

reduce completely 8.5 g of copper oxide to copper ?

Answer: 6.95 g

View Text Solution

98. An hourly requirement of an astronaut can be satisfied by the energy released when 34 grams of

sucrose `(C_(12)H_(22)O_(11))` are burnt in his body. How many grams of oxygen would be require to carry

in space capsule to meet his requirement for one day (24 hours) ?

Answer: 916.2 g

View Text Solution

99. 5.82 g of a silver coin is dissolved in nitric acid. One adding solution, all the silver present gets

precipitated as AgCl. The weight of the precipitate is found to be 7.20 g. What is the percentage of silver in

the coin ?

Answer: `93.1 %`

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100. 0.5 mole of calcium carbonate id decomposed by an aqueous solution containing 25 % JCl by mass.

Calculate the mass of the solution consumed.

Answer: 146 g

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101. 4.6 g of sodium is treated with excess of water. Calcium the volume of hydrogen evolved at N.T.P

Answer: 2240 mL

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102. 1.0 g of a mixture of carbonates of calcium and magnesium gave `240 cm^(3)` of `CO_(2)` at N.T.P

Calculate the percentage composition of the mixture.

Answer: `CaCO_(3)=62.5 %, MgCO_(3)=37.5 %`

View Text Solution

103. 10 grams of a sample of potassium chlorate gave on complete decomposition 2.24 litre of oxygen at

N.T.P. What is the percentage purity of the sample ?

Answer: `81.7 %`

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104. A sample of hydrochloric acid contains 20 % hydrochloric acid by weight. How much of this acid is

required for the complete reduction of 50 g of calcium carbonate ?

Answer: 182.5 g

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105. Calculate the volume of carbon dioxide at N.T.P evolved by strong heating of 20 g of calcium

carbonate.

Answer: 4.48 L

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106. What quantity of copper (II) oxide will 2.80 litres of hydrogen at N.T.P. ?

Answer: 9.94 g

View Text Solution

107. What volume of hydrogen at N.T.P would be liberated by the action of 50 mL of dilute `H_(2)SO_(4)` of

40 % purity and having a specific gravity of `1.3 g mL^(-1)` on 65 g of zinc ? (Atomic mass of Zn = 65) ?

Answer: 5.94 L

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108. Calculate the volume of oxygen at N.T.P that would be required to convert 5 litres of carbon monoxide

into carbon dioxide.

Answer: 2.5 L

View Text Solution

109. A gaseous mixture of 3 L of propane `(C_(3)H_(8))` and butane `(C_(4)H_(10))` on complete

combustion at `25^(@)C` produced 10 L of `CO_(2)`. Find out the composition of the gaseous mixture.

Answer: 2 L, 1L

View Text Solution

110. 1 litres of oxygen is allowed to react with three litres of carbon monoxide at N.T.P. Calculate the volume

of each gas found after the reaction.

Answer: 1 L, 2L

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111. The thermit rection used to weld iron rails in building a rail track, involves the following reaction

`Fe_(2)O_(3)+2AlrarrAl_(2)O_(3)+2Fe`

Calculate the mass of iron metal that can be prepared from 150 g of aluminium and 250 g of iron (iii) oxide.

Answer: 175 g of Fe

View Text Solution

112. Assume that 4g of `I_(2)` are allowed to react with 4g of Mg metal according to the following equation

`Mg+I_(2) rarr MgI_(2)`

Which is the limiting reagent in the reaction ?

Answer: `I_(2)`

View Text Solution

113. Calculate the amount of NaOH present in 200 mL of 0.5 N solution.

Answer: 4 g

View Text Solution

114. What volume of water should be added to 300 mL of 0.5 M NaOH solution so as to get a solution of 0.2

M ?

Answer: 450 mL

View Text Solution

115. 5.3 g of sodium carbonate have been dissolved in 500 mL of the solution. What is the molarity of the

solution ?

Answer: 0.1 M

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116. A solution is prepared by dissolving 18.25 g NaOH in 200 mL of it. Calculate the molarity of the

solution.

Answer: 2.281 M

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117. A bottle of commercial sulphuric acid (density = 1.787 gm/mL) is labelled 86 percent by weight. What is

the molarity of the solution ? What volime of the acid is required to make it 1 litre of 0.2 M `H_(2)SO_(4)` ?

Answer: (i) 15.68 M (ii) 12.75 mL

View Text Solution

118. What will be normality of the solution obtained by adding 200 mL of pure water to 100 mL of 0.2 N HCl

solution ?

Answer: 0.067 N

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119. What volume of 10 M HCl and 3M HCl should be mixed to get 1 L of 6M HCl solution ?

Answer: Volume of 10 M HCl = 428 mL ; Volume of 3M HCl = 572 mL

View Text Solution

120. How many moles and how many grams of sodium chloride are present in 250 mL of 0.5 M NaCl

solution ?

Answer: 0.125 mol, 7.3 g

View Text Solution

121. Calculate the molality of 1M solution of sodium nitrate. The density of solution is `1.25 "g cm"^(-3)`

Answer: 0.86 m

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122. 4 litres of water are added to 2 litres 6 molar hydrochloric acid solution. What is the molarity of the

resulting solution ?

Answer: 2 M

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123. Calculate the molality of a solution containing 20.7 g of potassium carbonate in 500 mL of solution

(assume density of solution `= "1g mL"^(-1)`)

Answer: 0.313 m

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124. The molality of a solution of ethyl alcohol in water in 1.55 m. How many grams of ethyl alcohol are

dissolved in 2kg of water ?

Answer: 142.6 g

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125. A solution of naphthalene in benzene is 3 % by mass of naphthalene. What is the mass percentage of

benzene ?

Answer: `97 %`

Watch Video Solution

126. A solution contains 20 g of sodium chloride in `95 cm^(3)` solution. The density of solution is `1.25 "g

cm"^(-3)`. What is the mass percent of NaCl ?

Answer: `16.84 %`

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127. A solution has been prepared by dissolved 60 g of methyl alcohol in 120 g of water. What is the mole

fraction of methyl alcohol and water ?

Answer: (i) 0.220 (ii) 0.780

View Text Solution

128. Calculate the molarity of sulphuric acid solution in which mole fraction water is 0.85.

Answer: 9.8

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129. Concentration of glucose `(C_(6)H_(12)O_(6))` in normal blood is approximately 90 mg per 100 mL.

What is the molarity of glucose in blood ?

Answer: 0.005 M

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130. Hydrochloric acid is sold commercially as 12M solution. How many moles and how many grams of HCl

are present in 300 mL of 12.0 M solution ?

Answer: 3.6 mol, 131.4 g of HCl

View Text Solution

131. Calculate the mass percent of benzene `(C_(6)H_(6))` and carbon tetrachloride `(C Cl_(4))` if 22 g

benzene is dissolved in 122 g of carbon tetrachloride.

Answer: `15.28 %. 84.72 %`

Competitive (MCQ)

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132. Calculate the mass of urea `(NH_(2)CONH_(2))` required to prepare 2.5 kg of 0.25 molal aqueous

solution.

Answer: 37.5 g

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133. 0.48 g of a sample of a compound containing boron and oxygen contains 0.192 g of boron and 0.288 g

of oxygen. What is the percentage composition of the compound ?

Answer: B = 40 %, 0 = 60 %

View Text Solution

1. Which weighs the maximum ?

A. 2.24 litres of `CO_(2)` at N.T.P

B. `6.022 xx 10^(23)` molecules of `CO_(2)`

C. `6.022 xx 10^(23)` molecules of `CO_(2)`

D. 10 g of `CO_(2)`

Answer: B

View Text Solution

2. The number of atoms in 4.25g of `NH_(3)` is approximately :

A. `1 xx 10^(23)`

B. `2xx 10^(23)`

C. `4 xx 10^(23)`

D. `6 xx 10^(23)`

Answer: D

View Text Solution

3. The number of molecules in 16g of methane is :

A. `3.0 xx 10^(23)`

B. `6.022 xx 10^(23)`

C. `16//6.022 xx 10^(23)`

D. `16//3.0 xx 10^(23)`

Answer: B

View Text Solution

4. 4.4 g of an unknown gas occupies 2.24 L of volume under N.T.P. conditions. The gas may be :

A. `CO_(2)`

B. CO

C. `O_(2)`

D. `SO_(2)`

Answer: A

View Text Solution

5. The number of moles of oxygen in 1L of air which contains 21% oxygen by volume under standard

conditions is :

A. 0.186 mol

B. 0.21 mol

C. 2.10 mol

D. 0.0093 mol

Answer: D

View Text Solution

6. The maximum amount of `BaSO_(4)` precipitated on mixing `BaCl_(2)(0.5 M)` with `H_(2)SO_(4) (1M)`

will correspond to :

A. 0.05 M

B. 0.5 M

C. 1.0 M

D. 2.0 M

Answer: B

View Text Solution

7. One molal solution contains 1 mole of a solute in :

A. 1000 g of the solvent

B. one litre of the solvent

C. one litre of the solution

D. 22.4 litres of the solution

Answer: A

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8. Given the number : 161 cm, 0.161 cm and 0.0161 cm. The no. of significant figures for the three numbers

are

A. 3,4,5

B. 3,3,3

C. 3,3,4

D. 3,4,4

Answer: B

View Text Solution

9. Haemoglobin contain 0.33 % of iron by weight. The molecular mass of haemoglobin is approximately

67200. The number of iron atoms (At mass Fe = 56) present in one molecule of haemoglobins is :

A. 6

B. 1

C. 4

D. 2

Answer: C

View Text Solution

10. How many grams of dibasic acid (molecular mass 200) should be present in 100 mL of the aqueous

solution to give 0.1 N solution ?

A. 1g

B. 2g

C. 10 g

D. 20 g

Answer: A

View Text Solution

11. Assuming fully decomposed, the volume of `CO_(2)` released at N.T.P on heating 9.85 g of `BaCO_(3)`

(Atomic mass of Ba = 137) will be :

A. 0.84 L

B. 2.24 L

C. 4.06 L

D. 1.12 L

Answer: D

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12. The specific heat of a metal is 0.16. It appoximate atomic mass would be :

A. 32

B. 16

C. 40

D. 64

Answer: C

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13. Which has the maximum number of atoms ?

A. `6.022 xx 10^(21)` molecules of `CO_(2)`

B. 22.4 L of `CO_(2)` at N.T.P

C. 0.44 of `CO_(2)`

D. None of these

Answer: B

View Text Solution

14. The mass of `CaCO_(3)` produced when carbon dioxide is bubbled through 500 mL of 0.5 M

`Ca(OH)_(2)` solution will be :

A. 25 g

B. 50 g

C. 20 g

D. 10 g

Answer: A

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15. One gram of a metallic oxide on reduction gives 0.68 g of the metal. The equivalent mass of the metal is

:

A. 68

B. 34

C. 51

D. 17

Answer: D

View Text Solution

16. 2.5 litres of 1M NaOH solution is mixed with 3.0 litres of 0.5 M NaOH solution. The molarity of resulting

solution is :

A. 0.80 M

B. 1.0 M

C. 0.73 M

D. 0.50 M

Answer: C

View Text Solution

17. Given the numbers : 786, 0.786 and 0.0786 cm. The number of significant figures for the three numbers

is :

A. 3,4 and 5

B. 3,3 and 3

C. 3, 3 and 4

D. 3, 4 and 4

Answer: B

View Text Solution

18. The weight of one molecule of compound `C_(60)H_(22)` is :

A. `1.2 xx 10^(-20) g`

B. `1.4 xx 10^(-21) g`

C. `5.025 xx 10^(23)g`

D. `6.023 xx 10^(23)g`

Answer: B

View Text Solution

19. The litres of `CO_(2)` represented by 4.4 g of `CO_(2)` at S.T.P are :

A. 2.4 litres

B. 2.24 litres

C. 44 litres

D. 22.4 litres

Answer: B

View Text Solution

20. The weight of pure NaOH required to prepare 250 mL of 0.1 N solution is :

A. 4 g

B. 2 g

C. 1 g

D. 5 g

Answer: C

View Text Solution

21. Maximum number of molecules are present in

A. 15 L of `H_(2)` gas at S.T.P

B. 5 L of `N_(2)` gas at S.T.P

C. 0.5 of `H_(2)` gas

D. 10 g of `O_(2)` gas

Answer: A

View Text Solution

22. If 30 mL of `H_(2)` and 20 mL of `O_(2)` react to form water, what is left at the end of the experiment ?

A. 10 mL of `H_(2)`

B. 5 mL of `H_(2)`

C. 10 mL of `O_(2)`

D. 5 mL of `O_(2)`

Answer: D

View Text Solution

23. The crystalline salt `Na_(2)SO_(4)` on heating loses 55.9 % of its weight. The formula of the crystalline

salt is :

A. `Na_(2)SO_(4).5H_(2)O`

B. `Na_(2)SO_(4).7H_(2)O`

C. `Na_(2)SO_(4).2H_(2)O`

D. `Na_(2)SO_(4).10H_(2)O`

Answer: D

View Text Solution

24. The number of moles of `KNnO_(4)` that will be needed to react with one mole of sulphite ion in acidic

solution is :

A. `4//5`

B. `2//5`

C. 1

D. `3//5`

Answer: B

View Text Solution

25. How many moles of lead (II) chloride are formed from a reaction between 6.5 g of PbO and 3.2 of HCl ?

A. 0.011

B. 0.029

C. 0.044

D. 0.333

Answer: B

View Text Solution

26. Volume occupied by one molecule of water (density `"1 g cm"^(-3)`) is :

A. `3.0 xx 10^(-23) cm^(3)`

B. `5.5 xx 10^(23) cm^(3)`

C. `9.0 xx 10^(-23) cm^(3)`

D. `6.023 xx 10^(-23) cm^(3)`

Answer: A

View Text Solution

27. 10 g of hydrogen and 64 g of oxygen were filled in a steel vessel and exploded. Amount of water

produced in the reaction will be :

A. 3 mol

B. 4 mol

C. 1 mol

D. 2 mol

Answer: B

View Text Solution

28. How many moles of iodine are liberated when 1 mole of potassium dichromate react with excess of

potassium iodide in the presence of concentrated sulphuric acid ?

A. 1

B. 2

C. 3

D. 4

Answer: C

View Text Solution

29. The number of atoms in 0.1 mole of triatomic gas is :

A. `6.026 xx 10^(22)`

B. `1.806 xx 10^(23)`

C. `3.6 xx 10^(23)`

D. `1.8 xx 10^(22)`

Answer: B

View Text Solution

30. If 1.5 moles of oxygen combine with Al to form `Al_(2)O_(3)`. The mass of Al in grams. (Atomic mass of

Al = 27) used in the reaction is :

A. 2.7

B. 54

C. 40.5

D. 81

Answer: B

View Text Solution

31. Which has maximum number of molecules among the following ?

A. 44 g of `CO_(2)`

B. 48 g of `O_(3)`

C. 8 g of `H_(2)`

D. 64 g of `SO_(2)`

Answer: C

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32. How many grams of concentrated nitric acid solution should be used to prepare 250 mL of 2.0 M

`HNO_(3)` solution ? The concentration of nitric acid is 70 % by mass.

A. 54.0 g conc. `HNO_(3)`

B. 45.0 g conc. `HNO_(3)`

C. 90.0 g conc. `HNO_(3)`

D. 70.0 g conc. `HNO_(3)`

Answer: B

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33. 1.0 g of magnesium is burnt with 0.56 g of `O_(2)` in a closed vessel. Which reactant is left in excess

and how much ?

A. Mg , 0.44 g

B. `O_(2)` , 0.28 g

C. Mg , 0.16 g

D. `O_(2)` , 0.16 g

Answer: C

View Text Solution

34. When 22.4 litres of `H_(2)(g)` is mixied with 11.2 litres of `Cl_(2)(g)`, each at S.T.P, the moles of HCl (g)

formed is equal to :

A. 0.5 mol of HCl (g)

B. 1.5 mol of HCl (g)

C. 1.0 mol of HCl (g)

D. 2.0 mol of HCl (g)

Answer: C

View Text Solution

35. Mole fraction of solute in a 2.0 molal aqueous solution is :

A. 1.77

B. 1.87

C. 0.347

D. 0.0347

Answer: D

View Text Solution

36. What is the mass of the precipitate formed when 50 mL of 16.9 % solution of `AgNO_(3)` is mixed with

50 mL of 5.8 % `NaCl` solution ?

`(Ag = 107.8,N=14,O=16,Na=23,Cl=35.5)`

A. 3.5 g

B. 7 g

C. 14 g

D. 28 g

Answer: B

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37. The number of water molecules is maximum in :

A. 1.8 g of water

B. 18 g of water

C. 18 moles of water

D. 18 molecules of water

Answer: C

View Text Solution

38. What is the mole fraction of the solute in a 1.0 m aqueous solution ?

A. `1.770`

B. `0.0354`

C. `0.0177`

D. `0.177`

Answer: C

View Text Solution

39. 20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g

magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample ? (At. Wt of

Mg = 24)

A. 96

B. 84

C. 60

D. 75

Answer: B

View Text Solution

40. If Avogadro number `N_(A)`, is changed from `6.022 xx 10^(23) mol^(-1)` to `6.022 xx 10^(20) mol^(-1)`,

this would change

A. the mass of one mole of carbon

B. the ratioof chemical species to each other in a balanced equation

C. the ratio of elements to each other in a compound

D. the definition of mass in units of grams

Answer: A

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41. Which one of the following has maximum number of molecules ?

A. 16 g of `O_(2)`

B. 16 g of `NO_(2)`

C. 4 g of `N_(2)`

D. 32 g of `N_(2)`

Answer: D

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42. The density of 2.0 M solution of a solute is `1.2 g mL^(-1)`. If the molecular mass of the solute is `100 g

mol^(-1)`, then the molality of the solution is

A. 2.0 m

B. 1.2 m

C. 1.0 m

D. 0.6 m

Answer: A

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43. Suppose the elements X and Y combine to form two compounds of `XY_(2) and X_(3)Y_(2)`. When 0.1

mole of `XY_(2)` weighs 10 g and 0.05 mole of `X_(3)Y_(2)` weighs 9 g , what are tha atomic masses of X

and Y ?

A. 40,30

B. 60,40

C. 20,30

D. 30,20

Answer: A

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JEE (Main)

44. A solution contains 4 g of NaOH and 16.2 g of water. The mole fraction of solute and solvent are

respectively.

A. 0.1,0.9

B. 0.2,0.8

C. 0.5,0.5

D. 0.4,0.6

Answer: A

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45. No. of moles in 100 mg of heptane is …………than those in 10 mg of propyne

A. 4 times greater

B. 4 times lesser

C. 2.5 times greater

D. 2.5 times lesser

Answer: A

View Text Solution

1. The numbers of significant figures in 0.0500 are

A. One

B. Three

C. Two

D. Four

Answer: B

View Text Solution

2. The correctly reported answer of the addition of `29*4406`, `3*2` and `2*25` will have significant figures

A. Three

B. Four

C. Two

D. Five

Answer: A

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3. The correctly reported answer of the addition of `294*406, 280*208` and 24 will be

A. 598.61

B. 599

C. 598.6

D. 598.614

Answer: B

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4. On dividing `0*25` by `22*1176`, the actual answer is `0*011303`. The correctly reported answer will be

A. 0.011

B. 0.01

C. 0.0113

D. 0.013

Answer: A

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5. Two student X and Y report the mass of the same substance as `7*0 g` and `7*00 g` repectively. Which of

the following statement is correct?

A. Both are equally accurate

B. X is more accurate than Y

C. Y is more accurate than X

D. Both are inaccurate scientifically

Answer: C

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6. One 'u' stands for :

A. An atom of carbon (C-12)

B. 1/12 of the carbon atom (C-12)

C. 1/12th of hydrogen atom

D. one atom of all the elements

Answer: B

View Text Solution

7. Two students performed the same experiment separately and each one of them recorded two readings of

mass which are given below. However, the correct reading is 5.0 g. On the basis of the data, mark the

correct option

`{:("Student",:underset("(i) (ii)")("Readings")),("A","5.01 4.99"),("B","5.05 4.95"):}`

A. Results of both the students are neither accurate nor precise

B. Results of student A are both accurate and precise

C. Results of student B are neither precise nor accurate

D. Results of student B are both precise and accurate

Answer: B

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8. All ammonium salts on heating with sodium hydroxide produce ammonia gas. From which ammonium

salt, can maximum amount of ammonia be obtained ?

A. `0.5 mol (NH_(4))_(3)PO_(4)`

B. `0.5 mol (NH_(4))_(2)SO_(4)`

C. `1.0 mol NH_(4)Cl`

D. `1.0 mol NH_(4)NO_(3)`

Answer: A

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9. 1 g of Mg is burnt in a closed vessel containing 0.5 g of `O_(2)`. Which of the following statements is

correct ?

A. `O_(2)` is the limiting reagent and Mg is in excess by 0.25 g

B. Mg is the limiting reagent and is in excess by 0.5 g

C. `O_(2)` is the limiting reagent and is in excess by 0.25 g

D. `O_(2)` is the limiting reagent and Mg is in excess by 0.75 g

Answer: A

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10. Boron occurs in nature in the form of two isotopes having atomic masses 10 and 11. What are the

percentage abundances of these isotopes in a simple a boron having average atomic mass of 10.8 are :

A. 20,80

B. 80,20

C. 50,50

D. 40,60

Answer: A

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11. In a compound, C, H and N are present in the ratio `9 : 1: 3.5` by weight. If the molecular weight. If the

molecular weight of the compound is 108. Molecular formula of the compound is :

A. `C_(2)H_(6)N_(2)`

B. `C_(3)H_(4)N`

C. `C_(6)H_(8)N_(2)`

D. `C_(9)H_(12)N_(3)`

Answer: C

View Text Solution

12. 25 mL of a solution of barium hydroxide on titration with a 0.1 molar solution of hydrochloric acid gave a

titre value of 35 mL. The molarity of barium hydroxide solution was :

A. 0.28

B. 0.35

C. 0.07

D. 0.1

Answer: C

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13. `6.022 xx 10^(20)` molecules of urea are present in 100 mL of its solution. The concentration of urea

solution is :

A. 0.001 M

B. 0.01 M

C. 0.02 M

D. 0.1 M

Answer: B

View Text Solution

14. How many moles of magnesium phosphate, `Mg_(3)(PO_(4))_(2)` will contain 0.25 mole of oxygen

atoms ?

A. 0.02

B. `3.125 xx 10^(-2)`

C. `1.25 xx 10^(-2)`

D. `2.5 xx 10^(-2)`

Answer: B

View Text Solution

15. Mass of `CO_(2)` is 88 g. The number of atoms of oxygen present is :

A. `2.41 xx 10^(24)`

B. `1.2 xx 10^(23)`

C. `1.4 xx 10^(23)`

D. `2.41 xx 10^(23)`

Answer: A

View Text Solution

16. Formula of cane sugar is `C_(12)H_(22)O_(11)`. No. of molecules present in 34.2 g of cane sugar is

A. `6.022 xx 10^(21)`

B. `6.022 xx 10^(20)`

C. `6.022 xx 10^(22)`

D. `6.022 xx 10^(18)`

Answer: C

View Text Solution

17. No. of `H_(2)O` molecules in a drop of water weighing 0.05 g is :

A. `1.15 xx 10^(23)`

B. `1.672 xx 10^(21)`

C. `1.5 xx 10^(20)`

D. `6.022 xx 10^(22)`

Answer: B

View Text Solution

18. The correct sequence of deceasing mass of the following is :

(i) `6.022 xx 10^(23)` atoms of oxygen

(ii) `1.0 xx 10^(23)` molecules of `H_(2)S`

(iii) `6.022 xx 10^(23)` molecules of oxygen

A. (i) `gt` (ii) `gt` (iii)

B. (i) `gt` (iii) `gt` (ii)

C. (iii) `gt` (i) `gt` (ii)

D. (ii) `gt` (i) `gt` (iii)

Answer: C

View Text Solution

19. The density `("in g mL"^(-1))` of a 3.60 M sulphuric acid solution that is 29 % of acid by mass is : (Given

molar mass `= 98 g mol^(-1)`)

A. 1.45

B. 1.64

C. 1.88

D. 1.22

Answer: D

View Text Solution

20. 200 mL of water is added to 500 mL of 0.2 M solution. What is the molarity of the diluted solution ?

A. 0.5010 M

B. 0.2897 M

C. 0.7093 M

D. 0.1428 M

Answer: D

View Text Solution

21. The molarity of NaOH solution obtained by dissolving 4g of it in 250 mL solution is :

A. 0.4 M

B. 0.8 M

C. 0.2 M

D. 0.1 M

Answer: A

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22. The density of a solution prepared by dissolving 120 g of urea (mol. Mass=60 u) in 1000 g of water is

1.15 g/mL. The molarity if this solution is

A. 1.78 M

B. 1.02 M

C. 2.05 M

D. 0.50 M

Answer: C

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23. The number of `H_(2)O` molecules in a drop of water weighing 0.018 g is :

A. `6.022 xx 10^(26)`

B. `6.022 xx 10^(23)`

C. `6.022 xx 10^(19)`

D. `6.022 xx 10^(20)`

Answer: D

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24. Number of molecules in 16 g of methane is :

A. `3.011 xx 10^(23)`

B. `6.022 xx 10^(23)`

C. `12.46 xx 10^(23)`

D. `1.5 xx 10^(23)`

Answer: B

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25. What is the molality of a solution containing 200 mg of urea (molar mass `= 60 g mol^(-1)`) ?

A. 0.0825

B. 0.825

C. 0.498

D. 0.0014

Answer: A

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26. A 5.82 g silver coin is dissolved in nitric acid. When sodium chloride is added to the solution, all the

silver gets precipitated as AgCl. The percentage of silver in the coin is :

A. `60.3 %`

B. `80 %`

C. `93.1 %`

D. `70 %`

Answer: C

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27. 25 mL of 3.0 HCl are mixed with 75 mL of 4.0 M HCl. If the volumes are additive, the molarity of the final

mixture will be :

A. 4.0 M

B. 3.75 M

C. 4.25 M

D. 3.50 M

Answer: B

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28. Which amount of dioxygen (in grams) contains `1.8 xx 10^(22)` molecules ?

A. `0.960`

B. `96.0`

C. `0.0960`

D. `9.60`

Answer: A

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29. If 12 g of water is formed during complete combustion of pure propene `(C_(3)H_(6))`, the mass of

propene burnt is :

A. 42 g

B. 21 g

C. 14 g

D. 56 g

Answer: B

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Comprehension

30. When 2.46 of hydrated salt `(MSO_(4)x H_(2)O)` is completely dehydrated, 1.20 g of anhydrous salt is

obtained. It molecular weight of anhydrous salt is `120 g mol^(-1)`, the value of x is

A. 2

B. 4

C. 5

D. 7

Answer: D

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31. The density of 3 M solution of NaCl is `1.25 "g L"^(-1)`. The molality of the solution is :

A. 2.79

B. 1.79

C. 0.79

D. 2.98 M

Answer: A

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1. Atoms and molecules are so small in size that it is neither possible to count them individually nor possible

to determine their mass. These are counted collectively in terms of Avogadro's number. The mass of

Avogadro's number of atoms and molecules is known as gram atomic mass and gram molecular mass

respectively. The volume occupied by Avogadro's number of molecules of a gas or vapours is known as

molar volume.

If `N_(A)` is Avogadro's number, then the number of valence electrons in 4.2 g of nitride ions `(N^(3-))` is :

A. `4.2 N_(A)`

B. `2.4 N_(A)`

C. `1.6 N_(A)`

D. `3.2 N_(A)`

Answer: B

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2. Atoms and molecules are so small in size that it is neither possible to count them individually nor possible

to determine their mass. These are counted collectively in terms of Avogadro's number. The mass of

Avogadro's number of atoms and molecules is known as gram atomic mass and gram molecular mass

respectively. The volume occupied by Avogadro's number of molecules of a gas or vapours is known as

molar volume.

The vapour density of a gas is 11.2. The volume occupied by 11.2 g of gas at NTP will be

A. 22.4 L

B. 11.2 L

C. 1 L

D. 44.8 L

Answer: B

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3. Atoms and molecules are so small in size that it is neither possible to count them individually nor possible

to determine their mass. These are counted collectively in terms of Avogadro's number. The mass of

Avogadro's number of atoms and molecules is known as gram atomic mass and gram molecular mass

respectively. The volume occupied by Avogadro's number of molecules of a gas or vapours is known as

molar volume.

The number of molecules in 16 g of methane is :

A. `3.0 xx 10^(23)`

B. `(16)/(6.022)xx10^(23)`

C. `6.022 xx 10^(23)`

D. `(16)/(3.0) xx 10^(23)`

Answer: C

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4. Atoms and molecules are so small in size that it is neither possible to count them individually nor possible

to determine their mass. These are counted collectively in terms of Avogadro's number. The mass of

Avogadro's number of atoms and molecules is known as gram atomic mass and gram molecular mass

respectively. The volume occupied by Avogadro's number of molecules of a gas or vapours is known as

molar volume.

If `3.01 xx 10^(20)` molecules are removed from 98 mg of `H_(2)SO_(4)`, then the number of moles of

`H_(2)SO_(4)` left will be

A. `0.1 xx 10^(-3)`

B. `1.66 xx 10^(-3)`

C. `9.95 xx 10^(-2)`

D. `0.5 xx 10^(-3)`

Answer: D

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5. In a binary solution, the component present in smaller proportion is called solute while the one in excess

is known as solvent. The solution containing 1 mole of the solute in 1L of solution is known as one molar

solution while the solution in which 1 mole of solute is dissolved in 1 kg of the solvent is called one molal

solution. The ratio of the no. of moles of a particular component to the total no. of moles in the solution is

known as its mole fraciton

The unit of molarity are

A. Moles

B. Moles/kg

C. Moles/litre

D. grams/litre

Answer: C

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6. In a binary solution, the component present in smaller proportion is called solute while the one in excess

is known as solvent. The solution containing 1 mole of the solute in 1L of solution is known as one molar

solution while the solution in which 1 mole of solute is dissolved in 1 kg of the solvent is called one molal

solution. The ratio of the no. of moles of a particular component to the total no. of moles in the solution is

known as its mole fraciton

The mole fraction of glycerine `C_(3)H_(5)(OH)_(3)` in a solution containing 36 g of water and 46 g of

glycerine is :

A. 0.46

B. `0.40`

C. `0.20`

D. 0.36

Answer: C

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7. In a binary solution, the component present in smaller proportion is called solute while the one in excess

is known as solvent. The solution containing 1 mole of the solute in 1L of solution is known as one molar

solution while the solution in which 1 mole of solute is dissolved in 1 kg of the solvent is called one molal

solution. The ratio of the no. of moles of a particular component to the total no. of moles in the solution is

known as its mole fraciton

The molality of pure water is :

A. 55.6

B. 50

C. 100

D. 18

Answer: A

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8. In a binary solution, the component present in smaller proportion is called solute while the one in excess

is known as solvent. The solution containing 1 mole of the solute in 1L of solution is known as one molar

solution while the solution in which 1 mole of solute is dissolved in 1 kg of the solvent is called one molal

solution. The ratio of the no. of moles of a particular component to the total no. of moles in the solution is

known as its mole fraciton

1.57 g of oxalic acid `(COOH)_(2)xH_(2)O` are dissolved in water and the volume is made upto 250 mL. On

titrating 6.68 mL of this solution requires 25 mL of N/15 NaOH solution for complete neutralisation. The

value of x is :

A. 3

B. 2

C. 4

D. 5

Answer: B

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9. Chemical reactions involve interaction of atoms and molecules. A large number of atoms and molecules

(approximately `6.022 xx 10^(23)`) are present in a few grams of any chemical compound varying with their

atomic/molecular masses. To handle such a large number conveniently, the mole concept was introduced.

This concept has implications in diverse areas such as analytical chemistry, biochemistry, electrochemistry

adn radiochemistry. The following examples illustrate a typical case involving chemical/electrochemical

reaction which requires a clear understanding of mole concept.

A 4.0 molar aqueous solution of NaCl is prepared and 500 mL of the solution is electrolysed. This lead to

the evolution of chlorine gas at one of electrodes (atomis mass : Na = 23 , Hg = 200 , 1F = 96500 C)

The total number of moles of chlorine gas evolved is :

A. 0.5

B. `1.0`

C. `2.0`

D. `3.0`

Answer: C

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10. Chemical reactions involve interaction of atoms and molecules. A large number of atoms and molecules

(approximately `6.022 xx 10^(23)`) are present in a few grams of any chemical compound varying with their

atomic/molecular masses. To handle such a large number conveniently, the mole concept was introduced.

This concept has implications in diverse areas such as analytical chemistry, biochemistry, electrochemistry

adn radiochemistry. The following examples illustrate a typical case involving chemical/electrochemical

Straight objective

reaction which requires a clear understanding of mole concept.

A 4.0 molar aqueous solution of NaCl is prepared and 500 mL of the solution is electrolysed. This lead to

the evolution of chlorine gas at one of electrodes (atomis mass : Na = 23 , Hg = 200 , 1F = 96500 C)

If the cathode is a Hg electrode, the maximum weight (g) of amalgam formed from the solution is :

A. 200

B. 225

C. 400

D. 446

Answer: D

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11. The total charge in coulombs required to complete the electrolysis is :

A. 24125

B. 48250

C. `96500`

D. `193000`

Answer: D

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1. If 0.5 mole of `BaCl_(2)` is mixed with 0.20 mole of `Na_(3)PO_(4)`, the maximum number of `Ba_(3)

(PO_(4))_(2)` that can be formed is :

A. `0.70`

B. `0.50`

C. `0.20`

D. `0.10`

Answer: D

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2. A molal solution is the one which contains one mole of the solute in

A. 1000 g of the solvent

B. one litre of the solvent

C. one litre of the solution

D. 22.4 litre of the solution

Answer: A

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3. The equivalent mass of `MnSO_(4)` is half its molecular mass when it is converted to

A. `Mn_(2)O_(3)`

B. `MnO_(2)`

C. `MnO_(4)^(-)`

D. `MnO_(4)^(2-)`

Answer: B

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4. In which mode of expression, the concentration of the solution is independent of the temperature ?

A. Molarity

B. Normality

C. Formality

D. Molality

Answer: D

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5. Find the number of `g`-molecules of oxygen in `6.023xx10^(24)CO` molecules.

A. 10 gm moles

B. 5 gm moles

C. 1 gm mole

D. 0.5 gm mole

Answer: B

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6. The correctly reported answer of addition of 29.4406,3.2 and 2.5 will have signifiant figures

A. 3

B. 5

C. 7

D. 10

Answer: A

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7. If `10^(21)` molecules are removed from 200 mg of `CO_(2)`, the number of moles of `CO_(2)` left will be

?

A. `2.88 xx 10^(-3)`

B. `1.66 xx 10^(-3)`

C. `4.54 xx 10^(-3)`

D. `1.66 xx 10^(-2)`

Answer: A

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8. The normality of 0.3 M phosphorus acid `(H_(3)PO_(3))` solution is :

A. 0.1

B. 0.9

C. 0.3

D. 0.6

Answer: D

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9. An aqueous solution of 6.3 g of oxalic acid dihydrate is made upto 250 mL. The volume of 0.1 N NaOH

required to completely neutralise 10 mL of this solution is :

A. 40 mL

B. 20 mL

C. 10 mL

D. 4 mL

Answer: A

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10. How many moles of electrons weigh one kilogram?

A. `6.023 xx 10^(23)`

B. `(1)/(9.108)xx10^(31)`

C. `(6.023)/(9.108)xx10^(54)`

D. `(1)/(9.108 xx 6.023)xx10^(8)`

Answer: D

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11. Which has maximum number of atoms ?

A. 24 g of C-12

B. 56g of Fe-56

C. 27 g of Al-27

D. 108 g of Ag-108

Answer: A

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12. Given that the abundances of isotopes `.^(54)Fe,.^(56)Fe`, and `.^(57)Fe` are 5%, 90%, and 50 %

respectively. The atomic mass of iron is :

A. 55.85

MCQ

B. 55.95

C. 55.75

D. 55.05

Answer: B

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13. Dissolving 120 g of urea (molecular mass = 60) in 1000 g of water gave a solution of density 1.15 g/mL.

The molarity of the solution is :

A. 1.78 M

B. 2.00 M

C. 2.05 M

D. 2.22 M

Answer: C

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1. Which of the following has the same mass ?

A. 0.1 mole of `O_(2)` gas

B. 0.1 mole of `SO_(2)` gas

C. `6.02 xx 10^(22)` molecule of `SO_(2)` gas

D. `1.204 xx 10^(23)` molecule of `O_(2)` gas

Answer: B::C::D

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2. Which of the following have the same number of significant figures ?

A. `0.050`

B. `0.50`

C. `5.0`

D. 50

Answer: A::B::C

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3. 8 g of `O_(2)` has the same number of molecules as in :

A. 11 g `CO_(2)`

B. 22 g `CO_(2)`

C. 7 g CO

D. 14 CO

Answer: A::C

Assertion-Reason

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4. Which of the following represent 32 g fo the substance ?

A. one mole of oxygen molecules

B. one gram atom of sulphur

C. `22.4 dm^(3)` of `O_(2)` gas at S.T.P

D. 1 gram mole of sulphur molecules

Answer: A::B::C

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1. Assertion : 22 carat gold is a mixture

Reason : A compound has fixed composition of the elements present in it.

A. If both assertion and reason are correct and reason is correct explanation for assertion

B. If both assertion and reason are correct but reason is not correct explanation for assertion

C. If assertion is correct but reason is incorrect

D. If both assertion and reason are incorrect

Answer: B

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2. Assertion : The standard unit of expressing mass of atoms is called 'u'

Reason : 'u' represents unit mass.

A. If both assertion and reason are correct and reason is correct explanation for assertion

B. If both assertion and reason are correct but reason is not correct explanation for assertion

C. If assertion is correct but reason is incorrect

D. If both assertion and reason are incorrect

Answer: C

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3. Assertion : In a gaseous reaction, the ratio of the volumes of gaseous reactants and products is in

agreement with their molar ratio

Reason : This is according to Avogadro's hypothesis.

A. If both assertion and reason are correct and reason is correct explanation for assertion

B. If both assertion and reason are correct but reason is not correct explanation for assertion

C. If assertion is correct but reason is incorrect

D. If both assertion and reason are incorrect

Answer: A

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4. Assertion : Empirical and molecular formulae of `NaHCO_(3)` are the same

Reason : Upon heating, `NaHCO_(3)` evolves `CO_(2)` gas.

A. Both assertion and reason are correct and reason is correct explanation for assertion

B. Both assertion and reason are correct but reason is not correct explanation for assertion

C. Assertion is correct but reason is incorrect

D. Both assertion and reason are incorrect

Answer: B

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5. Assertion : Both 32 g of `SO_(2)` and 8g of `CH_(4)` have same number of molecules

Reason : Equal moles of substances have equal number of molecules.

A. If both assertion and reason are correct and reason is correct explanation for assertion

B. If both assertion and reason are correct but reason is not correct explanation for assertion

C. If assertion is correct but reason is incorrect

D. If both assertion and reason are incorrect

Answer: A

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6. Assertion : Atomic mass of calcium is 40 u

Reason : An atom of calcium is 40 times heavier than an atom of carbon with mass 12 u.

A. If both assertion and reason are correct and reason is correct explanation for assertion

B. If both assertion and reason are correct but reason is not correct explanation for assertion

C. If assertion is correct but reason is incorrect

D. If both assertion and reason are incorrect

Answer: C

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7. Assertion : Relative atomic mass of boron is 10.8

Reason : Boron has two isotopes B-10 and B-11 with percentage abundance of 19.6 % and 80.4 %

respectively.

A. If both assertion and reason are correct and reason is correct explanation for assertion

B. If both assertion and reason are correct but reason is not correct explanation for assertion

C. If assertion is correct but reason is incorrect

D. If both assertion and reason are incorrect

Answer: A

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8. Assertion : 1 mole of N and 1 mole of `N_(2)` contain equal number of particles

Reason : 1 mole of molecules of always double than 1 mole of atoms in all the diatomic molecules.

A. If both assertion and reason are correct and reason is correct explanation for assertion

B. If both assertion and reason are correct but reason is not correct explanation for assertion

C. If assertion is correct but reason is incorrect

D. If both assertion and reason are incorrect

Answer: C

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9. Assertion : Components of a homogeneous mixture cannot be separated by using physical methods

Reason : Composition of homogeneous mixture is uniform throughtout as the components react to form a

single compound.

A. If both assertion and reason are correct and reason is correct explanation for assertion

B. If both assertion and reason are correct but reason is not correct explanation for assertion

C. If assertion is correct but reason is incorrect

D. If both assertion and reason are incorrect

Answer: D

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10. Assertion : Temperature below `0^(@)C` is possible on celsius scale but in Kelvin scale negative

temperature is not possible

Reason : The Kelvin scale is related to celsius scale as `K = .^(@)C - 273`.

A. If both assertion and reason are correct and reason is correct explanation for assertion

B. If both assertion and reason are correct but reason is not correct explanation for assertion

C. If assertion is correct but reason is incorrect

D. If both assertion and reason are incorrect

Answer: C

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11. Statement-1 : 2 moles of `BaCl_(2)` react with 3 moles of `Na_(3)PO_(4)` to form 0.66 mole of `Ba_(3)

(PO_(4))_(2)`

Statement-2 : `BaCl_(2)` is the limiting reactant and some `Na_(3)PO_(4)` remains unreacted.

A. Statement 1 is true, statement 2 is also true , statement 2 is the correct explanation of statement 1.

B. Statement 1 is true, statement 2 is also true , statement 2 is not the correct explanation of statement 1

C. Statement 1 is true, statement 2 is false

D. Statement 1 is fale, statement 2 is true

Answer: A

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12. Statement-1 : Atomic mass of sodium is 23u

Statement-2 : An atom of sodium is 23 times heavier than atom of C-12 isotope

A. Statement 1 is true, statement 2 is also true , statement 2 is the correct explanation of statement 1.

B. Statement 1 is true, statement 2 is also true , statement 2 is not the correct explanation of statement 2

C. Statement 1 is true, statement 2 is false

D. Statement 1 is fale, statement 2 is true

Answer: C

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13. Statement-1 : In the combustion of ethane, limiting reactant is ethane

Statement-2 : Oxygen in air is always present in excess.

A. Statement 1 is true, statement 2 is also true , statement 2 is the correct explanation of statement 1.

B. Statement 1 is true, statement 2 is also true , statement 2 is not the correct explanation of statement 3

C. Statement 1 is true, statement 2 is false

D. Statement 1 is fale, statement 2 is true

Answer: A

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14. Statement-1 : When NaOH and `H_(2)SO_(4)` solutions are mixed, the resulting solution is always

neutral

Matrix-Match

Statement-2 : Both NaOH and `H_(2)SO_(4)` are strong electrolytes and are completely dissociated in

aqueous solution.

A. Statement 1 is true, statement 2 is also true , statement 2 is the correct explanation of statement 1.

B. Statement 1 is true, statement 2 is also true , statement 2 is not the correct explanation of statement 4

C. Statement 1 is true, statement 2 is false

D. Statement 1 is fale, statement 2 is true

Answer: D

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15. Statement-1 : Both 10 g of sodium carbonate and 12 g of carbon have same number of carbon atoms

Statement-2 : Both contain 1g atoms of carbon which contains `6.022 xx 10^(23)` carbon atoms.

A. Statement 1 is true, statement 2 is also true , statement 2 is the correct explanation of statement 1.

B. Statement 1 is true, statement 2 is also true , statement 2 is not the correct explanation of statement 5

C. Statement 1 is true, statement 2 is false

D. Statement 1 is fale, statement 2 is true

Answer: A

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1. `{:(,"Column-I",,"Column-II"),("(A)","Atomic mass in grams","(p)","Mole"),("(B)","Gram molar mass","

(q)","Gram atom"),("(C)","Avogadro's No.","(r)",6.022xx10^(23)),("(D)","22.4 L of any gas at N.T.P.","

(s)","Molecular mass in grams"):}`

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2. `{:(,"Column-I",,"Column-II"),("(A)","Femto","(p)",10^(-9)),("(B)","Peta","(q)",10^(15)),("(C)","Giga","

(r)",10^(-15)),("(D)","Nano","(s)",10^(9)):}`

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3. `{:(,"Column-I",,"Column-II"),("(A)","Sea water","(p)","Compound"),("(B)","Phosphorus","

(q)","Heterogeneous mixture"),("(C)","Distilled water","(r)","Solution"),("(D)","Concrete","(s)","Element"):}`

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4. Match the amounts given in I with their no. of moles given in list II and select the correct answer using the

code given below :

`{:(,underset(("Amount"))("List-I"),,underset(("No.of moles"))("List-II")),("(P)","4480 mL of CO"_(2)" at

STP",1.,"0.1 mole"),("(Q)","0.1 g atom of iron",2.,"0.2 mole"),("(R)",1.5xx10^(23)"molecules of oxygen

gas",3.,"0.25 mole"),("(S)","9 mL of water",4.,"0.5 mole"):}`

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Example

A. `{:("P Q R S"),("1 2 3 4"):}`

B. `{:("P Q R S"),("4 2 1 3"):}`

C. `{:("P Q R S"),("2 1 3 4"):}`

D. `{:("P Q R S"),("4 3 1 2"):}`

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1. How will you justify that water is a compound ?

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2. Classify the following as pure substances or mixtures. Separate the pure substances into elements,

compounds and divide the mixtures into homogeneous and heterogeneous :

(i) Air (ii) Milk (iii) Graphite (iv) Gasoline (v) Diamond (vi) Tap water (vii) Distilled water (viii) Oxygen (ix)

Brass (x) 22 Carat gold (xi) Steel (xii) Iron (xiii) Sodium chloride (xiv) Iodised table salt.

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3. The room temperature in celsius scale is `25^(@)C`. Convert it into the other two scales of measurement.

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4. The body temperature of a normal healthy person is `98.4^(@)F`. What is the temperature on the celsius

scale ?

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5. Convert 2-6 minutes in seconds

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6. The wavelength of a beam of light is `5894 Ã…`. Express the value in nanometers.

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7. Convert 6 cubic metres into cubic centimetres.

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8. Express the following in `SI` units :

(i) 92 million miles (This is the distance between earth and sun)

(ii) 90 miles per hour (the typical speed of Rajdhani express)

(iii) 5 feet 4 inches (the average height of Indian female)

(iv) 0.74 Ã… (the bond length of hydrogen molecule)

(v) `45^(@)C` (the peak summer temperature n Jaipur)

(vi) 140 pounds (the average weight of Indian male).

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9. State the number of significant figures in the following numbers :

(i) 62.4

(ii) 0.050

(iii) 8.8674

(iv) 50.0.

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10. How many significant figures are present in the following ?

(i) 0.0025

(ii) 208

(iii) 126,000

(v) 600.0

(vi) 3.0034.

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11. What is the difference between 3.0 g and 3.00 g ?

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12. The population of India based on 1981 census figure was 684 millions. Express the results in scientific

notation and calculate the number of significant figures.

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13. Express the following in scientific notation

(i) `0.0048`

(ii) `236,000`

(iii) `8008`

(iv) `600.0`

(v) `500`

(vi) `783.4`.

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14. What is the number of significant figures in each of the following ?

(i) Mass of electron `= 9.108 xx 10^(-31) kg`

(ii) Mass of proton `= 1.672 xx 10^(-27) kg`

(iii) `0.00564`.

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15. Express the following numbers to four significant figures

(i) 5.607982

(ii) 32.392800

(iii) `1.78986xx10^(3)`

(iv) 0.007837.

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16. Add the numbers `28.521, 6.38 and 0.216` and report the final result correctly.

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17. `4.62 g` of sugar and `2.935 g` off table salt were mixed with `28.2 g` of water. What is the properly

reported mass of the solution ?

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18. The mass of copper metal is `6.342 g` and the density of copper is `7.6 g//cm^(3)`. What is its volume ?

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19. Round off the following upto three significant figures

(i) `34.246`

(ii) `10.4207`

(iii) `0.04587`

(iv) `10.668`.

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20. A student performs a titration with different burettes and find titre values of `25.2 mL, 25.25 mL and 25.0

mL`. What is the average titre value based upon rounded off principle ?

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21. What weight of sodium cloride decomposed by `4.9 g` of sulphuric acid, if 6 g of sodium hydrogen

sulphide `(NaHSO_(4))` and `1.825 g` of hydrogen chloride are produced in the same reaction ?

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22. When `4.2 g NaHCO_(3)` is added to a solution of `CH_(3)COOH` (acetic acid) weighing `10 g`, it is

observed that `2.2 g`of `CO_(2)` is released to the atmosphere. The residue is found to weigh `12.0 g`.

Show that these observations are in agreement with the law of conservation of mass.

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23. Weight of copper oxide obtained by heating `2.16 g` of metallic copper with `HNO_(3)` and subsequent

ingnition was `2.70 g`. In another experiment, `1.15 g` of copper oxide on reduction yielded `0.92 g` of

copper. Show that the results illustrate the law of definite proportions.

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24. Copper sulphate crystals contains `25.45 % Cu and 36.07 % H_(2)O`. If the law of constant composition

is true, calculate the weight of copper required to obtained `40 g` of crystalline copper sulphate.

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25. A metal forms two oxides. The higher oxide contains `80 %` metal. `0.72 g` of the lower oxide have `0.8

g` of higher oxide when oxidised. Show that the data illustrates the law of Multiple Proportions.

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26. Copper gives two oxides. On heating `1g` of each in hydrogen, we get `0.888 g and 0.798 g` of the

metal respectively. Show that these results are in agreement with the Law of Multiple Proportions.

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27. Carbon and hydrogen combine to form three compounds A, B, and C. The percentage of hydrogen in

these compounds are : `25,14.3 and 7.7` respectively. Show that the data illustrates the Law of Multiple

Proportions.

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28. `2.66 g` of chloride of a metal when treated with silver nitrate solution, gave `2.87 g` of silver chloride

`3.37 g` of another chloride of the same metal gave `5.74 g` of silver chloride when treated with silver nitrate

solution. Show that the results illustrate the law of multiple proportions.

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29. Phosphorus trichloride `(PCl_(3))` contains `22.57 %` of phosphorus, phosphine `(PH_(3))` contains

`91.18 %` of phosphorus. Hydrochloric acid `(HCl)` contains `97.23 %` of chlorine. Show that the data is

according to the Law of Reciprocal Proportions.

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30. Hydrogen sulphide `(H_(2)S)` contains `94.11 %` sulphur. Sulphur dioxide `(SO_(2))` contains `50 %`

oxygen and water `(H_(2)O)` contains `11.11 %` hydrogen. Shpw that the results are in agreement with the

law of reciprocal proportions.

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31. Aluminium oxide contains `52.9 %` aluminium and carbon dioxide contains `27.27 %` carbon. Assuming

that the law of Reciprocal proportions is true, calculate the percentage of aluminium in aluminium carbide.

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32. Two substances X and Y are colourless gases and are formed by the combination of sulphur and

oxygen. Substance X is obtained by the combination of `6.0 g` of sulphur of `6.0 g` of sulphur with `6.0 g` of

oxygen. Substance Y is formed when `8.6 g` of sulphur and `12.9` of oxygen combine.

(a) What is the mass ratio of the elements in the two substances ?

(b) Which law of chemical combination does it support ?

(c) Give the statement of the law.

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33. `0.44 g` of a hydrocarbon on complete combustion with oxygen gave `1.8 g` of water and `0.88 g` of

carbon dioxide. Show that these result are in agreement with the law of conservation of mass.

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34. `10 mL` of hydrogen combine with `5mL` of oxygen to yield water. When 200 mL of hydrogen at N.T.P.

are passed over heated `CuO`, the latter loses `0.144 g` of its mass. Do these results agree with the law of

constant composition ?

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35. `10 mL` of `H_(2)` contain 2000 molecules under certain temperature and pressure. Calculate the

number of molecules of oxygen whose volume is 150 mL at the same temperature and pressure.

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36. One volume of hydrogen combines with sulphur to produce one volume of gas (A). If the vapour density

of (A) be 17, what is its molecular formula ? Volumes have been measured under similar conditions of

temperature and pressure.

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37. The average atomic mass of copper is `63.5`. It exists as two isotopes which are `._(29)^(63)Cu and

._(29)^(65)Cu`. Calculate the percentage of each isotope present in it.

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38. Chlorine has two isotopes of atomic mass units `34.97 u and 36.97 u`. The relative abundances of these

two isotopes are `0.735 and 0.245` respectively. Find out the average atomic mass of chlorine.

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39. Calculate

(a) Mass of `2.5` gram atoms of magnesium,

(b) Gram atoms in `1.4` grams of nitrogen (Atomic mass : `Mg = 24,N=14`)

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40. (a) How many gram molecules are present in 4.9 g of `H_(2)SO_(4)` ?

(b) Calculate the mass of `0.72` gram molecules of `CO_(2)`.

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41. Fool's gold is so called because it bears a visual similarity to real gold. A block of fool's gold which

measures `1.50 cm xx 2.50 cm xx 3.00 cm` has a mass of `56.25 g`. How can this material be distinguished

from real gold by means of some physical property ? (Given density of real gold `= 19.3 g cm^(-3)`)

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42. Calculate the number of atoms in :

(i) 0.25 moles atoms of carbon

(ii) 0.20 mole molecules of oxygen.

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43. A flask P contains `0.5` mole of oxygen gas. Another flask `Q` contains `0.4` mole of ozone gas. Which

of the two flasks contains greater number of oxygen atoms ?

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44. How many atoms of each type present in 143 g of washing soda `(Na_(2)CO_(3).10H_(2)O)` ?

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45. How many atoms of oxygen and hydrogen are present in 0.15 mole of water ?

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46. Calculate the no. of moles of phosphorus in 92.9 g phosphorusm assuming that molecular formula of

phosphorus is `P_(4)`. Also calculate the no. of atoms and molecules of phosphorus in the sample.

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47. Calculate the total number of electrons present in 1.6 g of methane

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48. What is the numner of molecules of `CO_(2)` which contain 8g of `O_(2)` ?

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49. The electric charge on one electron is `1.602 xx 10^(-19)` coulomb. How much charge is present on 0.1

mole of `Cu^(2+)` ions ?

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50. Atmospheric air has `78 % N_(2) , 21 % O_(2) , 0.9 % Ar and 0.1 % CO_(2)` by volume. What is the

molecular mass of air in the atmosphere ?

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51. A cylinder of compressed gas contains nitrogen and oxygen in the molar ratio of `3:1`. If the cylinder

contains `2.5 xx 10^(4)g` of oxygen, what is the total mass of the gas in the mixture ?

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52. In a bank, there are as many coins as the number of molecules in `1.6 mug` of `CH_(4)`. How many

coins are there in the bank ?

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53. If Avogadro's number `(N_(A))` is changed from `6.022 xx 10^(23) mol^(-1)` to `6.022 xx 10^(20)

mol^(-1)`, what will be mass of 1 mole of carbon atoms ?

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54. What weight of calcium the same number of atoms as are present in 3.2g of sulphur ?

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55. From 200 mg of `CO_(2),10^(21)` molecules are removed. How many moles of `CO_(2)` are left ?

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56. The density of water at room temperature is 1.0 g/mL. How many molecules are there in a drop of wate

if its volume is 0.05 mL ?

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57. Calculate the weight of carbon monoxide having the same number of oxygen atoms as are present in

22g of carbon dioxide

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58. What is the molecular weight of a substance, each molecule of which contains `9` carbon atoms, `13`

hydrogen atoms and `2.33 xx 10^(-23) g` of other component ?

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59. The red colour of blood is due to haemoglobin. It contain `0.335` percent of iron. Four atoms of iron are

present in one molecule of haemoglobin. What is the molecular mass of haemoglobin ? (Given that the

atomic mass of Fe = 55.84)

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60. The density of a gaseous element is 5 times that of oxygen under similar conditions. If the molecule is

triatomic, what will be its atomic mass ?

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61. Calculate no. of carbon and oxygen atoms present in 11.2 litres of `CO_(2)` at N.T.P

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62. A sample of gaseous substance weighing 0.5 g occupies a volume of 1.12 litres under N.T.P. conditions.

Calculate the molar mass of the substance.

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63. How many molecules of `CO_(2)` are present in one litres of air containing 0.03 % volume of `CO_(2)`

at N.T.P ?

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64. Calculate the volume at N.T.P occupied by

(i) 14 g of nitrogen

(ii) 1.5 gram moles of carbon dioxide

(iii) `10^(21)` molecules of oxygen.

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65. Calculate

(a) the actual volume of a molecule of water

(b) the radius of a water molecule assuming to be spherical (density of water `= 1 g cm"^(-3)`)

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66. The cost of table salt `(NaCl)` and table sugar `(C_(12)H_(22)O_(11))` are Rs 2 per kg and Rs. 6 per kg

respectively. Calculate their cost per mole.

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67. Calculate the number of moles in each of the following :

(i) 392g of sulphuric acid

(ii) 44.8 g litres of sulphur dioxide at N.T.P

(iii) `6.022 xx 10^(22)` molecules of oxygen

(iv) 8 g of calcium.

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68. A coating of coabalt that is 0.005 cm thick is deposited on a plate that is `0.5 m^(2)` in total area. How

many atoms of cobalt are deposited on the plate ? (Density of cobalt `= 8.9 cm^(-3)` , Atomic mass of Co =

59 amu)

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69. Suppose the elements X and Y combine to form two compounds of `XY_(2) and X_(3)Y_(2)`. When 0.1

mole of `XY_(2)` weighs 10 g and 0.05 mole of `X_(3)Y_(2)` weighs 9 g , what are tha atomic masses of X

and Y ?

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70. How much copper can be obtained from `100g` of copper sulphate `(CuSO_(4))`?

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71. On analysing an impure sample of sodium chloride, the percentage of chlorine was found to be 45.5.

What is the percentage of pure sodium chloride in the sample ?

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72. `P` and `Q` are two elements which from `P_(2)Q_(3),PQ_(2)` molecules. If `0.15 "moles of"

P_(2)Q_(3)` and `PQ_(2)` weighs `15.9 g` and `9.3 g`, respectively, what are atomic weighs of `P` and `Q`?

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73. Sodium is an essential constituent of our body. Calculate the percentage of sodium in the breakfast

cereal which has been advertised to contain 40 mg of sodium per 50 g of the cereal.

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74. If the fertilizers are priced according to their nitrogen content, which will be the least expensive per 50 kg

bag ?

(a) Urea, `(NH_(2))_(2))CO`

(b) Ammonia `(NH_(3))`

(c) Ammonium nitrate `NH_(4)NO_(3)`

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75. A precipitate of `AgCl` and `AgBr` weighs `0.4066g`. On heating in a current of chlorine, the `AgBr` is

converted to `AgCl` and the mixutre loses `0.0725 g` in weight. Find the `%` of `Cl` in original mixture.

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76. A compound on analysis was found to contain `C = 34.6 %, H = 3.85 % and O = 61.55%` .Calculate its

empirical formula.

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77. An organic compound has the following percentage composition , `C = 48 %, H = 8 %, N = 28 %`.

Calculate the empirical formula of the compound.

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78. Silicon forms a compound with chlorine in which 5.6 g of silicon is combined with 21.3 og chlorine.

Calculate the empirical formula of the compound (Atomic mass : `Si = 28 , Cl = 35.5`)

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79. Two oxides of a metal contain `27.6%` and `30.0%` of Oxygen, respecttively. If the formula of the first be

`M_(3) O_(4)`. Find that of the second.

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80. A compound contains `42.3913 % K,15.2173 % Fe,19.5652 % C and 22.8260 % N`. The molecular

mass of the compound is 368 u. Find the molecular formula of the compound.

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81. A compound on analysis was found to contain the following composition :

`Na=14.31%,S=9.97%,O=69.50 %and H=6.22 %`

Calculate the molecular formula of the compound assuming that the whole of hydrogen in the compound is

present as water of crystallisation. Molecular mass of the compound is 322.

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82. A crystalline compound when heated become anhydrous by losing 51.2 % of the mass. On analysis, the

anhydrous compound gave the following percentage composition :

`Mg = 20.0 % , S = 26.66 % and O = 53.33 %`. Calculate the molecular formula of the anhydrous compound

and crystalline compound. The molecular mass of anhydride compound is 120 u.

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83. The chemical compounds are represented by both Empirical and Molecular formulae. Whereas the

former is only theoritical, the latter is the actual formula of a compound. In some cases, the two may be

even same. A very popular organic compound is a major constituent of alcoholic drinks.

(i) What is the empirical of the compound ?

(ii) What is its molecular formula ?

(iii) Give the chemical name of the compound

(iv) Find the percentage composition of the compound ?

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84. Gypsum is a hydrate of calcium sulphate 1.0 g of the sample contains 0.791 g of `CaSO_(4)`. How

many of `CaSO_(4)` are there in the sample ? Assuming that the rest of sample is water, how many moles

of water are there in the sample ? Show that the result is in consistent with the formula `CaSO_(4).2H_(2)O`

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85. Butyric acid contains only C, H and O. A 4.24 mg of sample butyric acid is completely burnt. It gives 8.45

mg of carbon dioxide and 3.46 mg of water. What is the mass percentage of each element in butyric acid ?

The molecular mass of buryric acid is determined by experiment as 88 amu. What is its molecular formula ?

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86. A compound (molecular mass 64.59 u) has the following data :

`{:("Element","Relative No. of atoms","% Composition"),("A",3.10,37.215),("B",7.80,7.8),("C",1.55,54.98):}`

Determine :

(i) Atomic masses of the elements A, B, C

(ii) Simplest atomic ratios of the element

(iii) Molecular formula of the compound.

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87. Write the chemical equation for the following reaction and balance the same by hit and trial method

Magnesium nitride + Water `rarr` Magnesium hydroxide + Ammonia.

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88. Acetylene burns in oxygen to form carbon dioxide and water. Write the skeleton equation for the reaction

and balance it.

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89. Balance the following chemical equation by partial equation method.

`Cu+HNO_(3)rarrCu(NO_(3))_(2)+NO+H_(2)O`

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90. By using partial equation method, balance the equation :

`NaOH+Cl_(2)rarrNaCl+NaClO_(3)+H_(2)O`.

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91. What mass of copper oxide will will be obtained by heating 12.35 g of copper carbonate ? (Atomic mass

of Cu = 63.5).

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92. Calculate the weight of lime (CaO) obtained by heating 200 kg of 95 % pure lime stone `(CaCO_(3))`

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93. How many moles of methane are required to produce 22g of `CO_(2)` on combustion ?

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94. 1 gram of pyrolusite `(MnO_(2))` was boiled with excess of concentrated `HCl` and the issuing gas was

passed through a solution of potassium iodide when 1.27 g of iodide were liberated. What is the percentage

of pure `MnO_(2)` in the sample ?

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95. An impure sample of sodium chloride which weighed 1.2 gram gave on treatment with excess of silver

nitrate solution 2.4 gram of silver chloride as the precipitate. Calculate the percentage purity of the sample.

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96. A mixture of `FeO` and `Fe_(3)O_(4)` when heated in air to a constant weight, gains 5% of its weight.

Find the composition of the intial mixutre.

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97. 1.84 g of a mixture of `CaCO_(3) and MgCO_(3)` is strongly heated till no further loss in mass takes

place. The residue is found to weigh 0.96 g. Calculate the percentage of each component in the mixture.

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98. 10 mL of a solution of `NaCl` gave on evaporation 0.93 g of the mixed salt which gave `1.865` of `AgCl`

by reacting with `AgNO_(3)` solution. Calculate the quantity of `NaCl` in 10 mL of the solution.

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99. What is the mass of the precipitate formed when 50 mL of 16.9% solution of `AgNO_(3)` is mixed with

50 mL of 5.8% NaCl solution?

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100. `KClO_(3)` on heating decomposes to give `KCl and O_(2)`. What is the volume of `O_(2)` at N.T.P

liberated by 0.1 mole of `KClO_(3)` ?

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101. What volume of air at N.T.P containing 21 % oxygen by volume is required to completely burn 1000 g

of sulphur containing 4 % incombustible matter ?

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102. What volume of hydrogen at N.T.P would be liberated by the action of 50 mL of dilute `H_(2)SO_(4)` of

40 % purity and having a specific gravity of `1.3 g mL^(-1)` on 65 g of zinc ? (Atomic mass of Zn = 65).

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103. Calculate the amount of `KClO_(3)` needed to supply sufficient oxygen for burning 112 L of CO gas at

N.T.P.

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104. What volume of oxygen at N.T.P is needed to cause the complete combustion of 200 mL of acetylene ?

Also calculate the volume of carbon dioxide formed.

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105. One litre of a mixture of CO and `CO_2` is passed through red-hot charcoal. The volume now becomes

1.6 litre. Find the composition of the mixture by volume.

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106. Under similar conditions of temperature and pressure,2 volumes of ozone `(O_(3))` on decomposition

give 3 volumes oxygen `(O_(2))`. 20 mL of the gaseous mixture when heated and then cooled expands to

21 mL. Find the percentage volume ozone in the gaseous mixture.

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107. 1.0 g of magnesium is burnt with 0.56 g `O_(2)` in a closed vessel. Which reactant is left in excess and

how much?

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108. 3.0 g of `H_(2)` react with 29.0 g `O_(2)` to yield `H_(2)O`

(i) What is the limiting reactant ?

(ii) Calculate the maximum amount of water that can be formed

(iii) Calculate the amount of one of the reactants which remains unreacted.

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109. 50.0 kg of `N_(2)(g) and 10.0 kg` of `H_(2)(g)` are mixed to produce `NH_(3)(g)`. Calculate mass of

`NH_(3)(g)` formed. Identify the limiting reagent in the production of `NH_(3)` in this situation.

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110. The reaction, `2C+O_(2)rarr2CO` is carried out by taking `24 g` of carbon and `96 gO_(2)`, find out:

(a) which reactant is left in excess?

(b) How much of it is left?

(c ) How many mole of `CO` are formed?

(d) How many `g` of other reactant should be taken so that nothing is left at the end of reaction?

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111. When a mixture of 10 moles of `SO_(2)` and 15 moles of `O_(2)` was passed over catalyst, 8 moles of

`SO_(3)` was formed. How many moles of `SO_(2)` and `O_(2)` did not enter into combination?

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112. 1 gm of a mixture of calcium carbonate and magnesium carbonate gave on ignition 240 mL of carbon

dioxide at S.T.P. What is the percentage composition of the mixture ?

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113. Gastric contains 3g `HCl` per litre. If a person produces 2.5 L of gastric juice per day, how many

actacid tables each containing 400 mg of `Al(OH)_(3)` are needed to neutralise all the `HCl` produced in

one produced in one day ?

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114. A solution gas been prepared by dissolving 5 g of urea in 95 g of water. What is the mass percent of

urea in the solution ?

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115. Calculate the masses of cane sugar and water required to prepare 250 g of 25 % solution of cane

sugar.

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116. On litre of sea water weighs 1050 grams and contains `6 xx 10^(-3)g` of dissolved oxygen gas.

Calculate the concentration of the dissolved oxygen in ppm.

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117. Calculate the mole fraction of benzene in a solution containing 30 % by mass of it in carbon

tetrachloride.

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118. Calculate the percentage composition in terms of mass of solution obtained by mixing 300 g of a 25 %

and 400 g of a 40 % solution by mass.

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119. What is molarity of the resulting solution obtained mixing `2.5 L` of 0.5 M urea solution and 500 mL of

2M urea solution ?

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120. What is the volume of ethyl alcohol (density 1.15 g/cc) that has to be added to prepare 100 cc of 0.5 M

ethyl alcohol solution in water ?

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121. A solution is prepared by dissolving 4g of NaOH to give 500 mL of it. Calculate the molarity of the

solution.

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122. What volume of 36 M and 1 M sulphuric acid must be mixed to get 1L of 6 M sulphuric acid ?

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123. What is the molality of a solution which contains 36 g of glucose `(C_(4)H_(12)O_(5))` in 250 g of water

?

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124. Concentrated aqueous solution of sulphuric acid is `98 %` by mas and has density of `1.80 "g

mL"^(-1)`. What is the volume of acid requird to male one litre `0.1 M H_(2)SO_(4)` solution ?

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125. `29.2 % (W//W) HCl` stock solution has a density of `1.25 "g mL"^(-1)`. The molecular mass of `HCl` is

`36.5 g mol^(1)`. What is the volume (mL) of stock required to prepare 200 mL of solution of `0.4 M HCl` ?

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126. The density of 2 molal aqueous solution of NaOH is `1.10 "gm L"^(-1)`. Calculate the molarity of the

solution.

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127. (a) Sample of NaOH weighing 0.38 is dissolved in water and the solution is made to 50.0 mL in a

volumetric flask. What is the molarity of the resulting solution ?

(b) How many moles of NaOH are contained in 27 mL of 0.15 M NaOH solution ?

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128. In a reaction vessel, 0.184 g of NaOH is required to be added for completing the reaction. How many

millilitres of 0.150 M NaOH solution should be added for this reaction ?

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129. Molarity of `H_(2)SO_(4)` is 0.1 M and its density is `1.06 g cm^(-3)`. What will be concentration of the

solution in terms of molarity and mole fraction ?

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130. Calculate the molarity of each of the following solutions `:`

`a. 30g` of `Co(NO_(3))_(2).6H_(2)O` in `4.3L` of solution

`b. 30mL` of `0.5 M H_(2)SO_(4)` diluted to `500mL`.

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131. Calculate the molality and molarity of 93 % `H_(2)SO_(4)` (weight/volume). The density of the solution

is `1.84 gmL^(-1)`

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132. What is molality of 1 M solution of sodium nitrate if its density is `1.25 "g cm"^(-3)` ?

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133. Calculate the molarity of water if its density is `1000 kg//m^(3)`.

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134. Calculate the molarity and normality of solution containing 3.15 of hydrated oxalic acid (`{:(COOH),(|),

(COOH):}.2H_(2)O`) dissolved in 250 mL of the solution.

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135. Calculate the number of molecules of oxalic acid `(H_(2)C_(2)O_(4).2H_(2)O)` in 100 mL of 0.2 N

oxalic acid solition.

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136. 20 mL of a solution of sulphuric acid neutrlise 21.2 mL of 30 % solution of sodium carbonate. How

much water should be added to 100 mL of this solution to bring down its strength to decinormal ?

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137. (a) A solution is prepared by dissolving `3.65 g` of `HCl` in 500 mL of the solution. Calculate the

normality of the solution

(b) Calculate the volume of this solution required to prepare 250 mL of 0.05 N solution.

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138. Calculate the `(a)` molality, `(b)` molartiy, and `(c)` mole fraction of `KI` if the density of `20% (` mass

`//` mass `)` aqueous `KI` is `1.202 g m L^(-1)`.

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139. An antifreeze solution is prepared from `222.6 g` of ethylene glycol `[C_(2)H_(4)(OH)_(2)]` and `200 g`

of water. Calculate the molality of the solution. If the density of the solution is `1.072g mL^(-1)` then what

shall be the molarity of the solution?

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140. How many grams of concentrated nitric acid solution should be used to prepare 250 mL of 2.0 M

`HNO_(3)` solution ? The concentration of nitric acid is 70 % by mass.

Board Examinations

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141. A compound `H_(2)X` with molar mass of 80 g is dissolved in a solvent having density of `0.4 g

mL^(-1)`. Assuming no change in volume upon dissolution, what is the molality of 3.2 M solution of the

compound ?

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142. The mole fraction of `CH_(3)OH` in an aqueous solution is 0.02 and density is `94 "g cm"^(-3)`,

Determine the molality of the solution.

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1. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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2. Calculate the molecular mass of the following:

a. `H_(2)O`

b. `CO_(2)`

c. `CH_(4)`

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3. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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4. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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5. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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6. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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7. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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8. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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9. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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10. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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11. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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12. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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13. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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14. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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15. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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16. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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17. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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18. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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19. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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20. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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21. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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22. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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23. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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24. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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25. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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26. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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27. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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28. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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29. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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30. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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31. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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32. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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33. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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N.C.E.R.T (Short answer)

34. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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35. Calculate the molecular mass of the following :

(i) `H_(2)O`

(ii) `CO_(2)`

(iii) `CH_(4)`

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1. What will be the mass of one `.^(12)C` atom in `g`?

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2. How many significant figures should b e present in the answer of the following calculations?

`(2.5xx1.25xx3.5)/(2.01)`

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3. What is the symbol for SI unit of mole? How is the mole defined?

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4. Distinguish between molarity and molality.

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5. Calculate the mass per cent of calcium, phosphorus and oxygen in calcium phosphate `Ca_(3)

(PO_(4))_(2)`.

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6. 45.4L of dinitrogen reacted with 22.7L of dioxygen and 45.4 L of nitrous oxide was formed the reaction is

given below

`2N_(2)(g)+O_(2)(g)rarr2N_(2)O(g)`

Which law is being obeyed in this experiment? Write the statement of the law?

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7. If two elements can combine to form more than one compound, the masses of one element that combine

with a fixed mass of the other element, are in whole number ratio.

(a) Is this statement true?

(b) It yes, according to which law?

(c) Give one example related to this law.

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8. Calculate the average atomic mass of hydrogen using the following data

Isotope % Natural abundance Molar mass

`.^(1)H 99.985 1`

`.^(2)H 0.015 2`

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9. Hydrogen gas is prepared in the laboratory by reacting dilute HCl with granulated zinc, Following reaction

takes place

`Zn+2HClrarrZnCl_(2)+H_(2)`

Calculate the voluem of hydrogen gas liberated at STP when 32.65 g of zinc reacts with HCl. 1 mol of a gas

occupies 22.7 L volume at STP, atomic mass of Zn=65 .3u

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10. The density of 3 molal solution of NaOH is 1.110g `mL^(-1)`. Calculate the molarity of the solution.

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N.C.E.R.T (Long answer)

11. Volume of a solution chagnes with chagne in temperature, then what will the molality of the solution be

affected by temperature? Give reason for your answer.

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12. If 4 g of NaOH dissovles in 36g of `H_(2)O`, calculate the mole fraction of each component in the

solution. (specific gravity of solution is `1g mL^(-1)`).

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13. The reactant which is entirely consumed in reaction is known as limiting reagent. In the reaction

`2A+4Brarr3C+4D`, when 5 moles of A react with 6 moles of B, then

(a) which is the limiting reagent?

(b) calculate the amount of C formed?

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1. A vessel contains 1.6g of dioxygen at STP(273.15k,1atm pressure). The gas is now trasnferred to

another vessel at constnat temperature. Whre pressure becomes half of the original pressure. Calculate

( a) Volume of the new vessel.

(b) number of molecuels of dioxygen.

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Concept Based Question

2. Calcium carbonate reacts with aqueous HCl to give `CaCl_(2)` and `CO_(2)` according to the reaction

given below

`CaCO_(3)(s)+2HCl(aq)rarrCaCl_(2)(aq)+CO_(2)(g)+H_(2)O(l)`

What mass of `CaCl_(2)` will be formed when 250mL of 0.76 M HCl reac ts with 1000 g of `CaCO_(3)`?

Name the limiting reagent. Calculate the number of moles of `CaCl_(2)` formed in the reaction.

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3. Define the law of multiple proportions, Explain it with two examples. How des this law point to the

existence of atoms?

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4. A b ox contains some identical red coloured balls. Labelleda as A, each weighing 2g. Another box

contains identicla blue coloured balls. Labelled as B, each weighing 5g. Consider combination

AB,`AB_(2),A_(2)B` and `A_(2)B_(3)` and show that law of multiple proportions is applicable.

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1. When do zeros present in a number become insignificant ?

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2. Is velocity a basic or derived quantity according to S.I system ?

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3. Which is more precise measurement of the length of a thread (i) 10.0 cm (ii) 10.00 cm ?

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4. Why do we regard the gaseous state of water as vapours while that of ammonia as gas ?

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5. Why is distilled water a compound while tap water a mixture ?

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6. Mixture of salt and water is a solution while that of oil and water is not. Explain.

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7. When is the law of definite proportions not obeyed ?

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8. Which law co-relates the mass and volume of a gas ?

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9. Atomic mass of oxygen is 16 u. What does it indicant ?

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10. An element has fractional atomic mass. What does it indicate ?

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11. What is the difference between the mass of a molecule and molecular mass ?

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12. Where do we use the words mole and mol ?

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13. Does one gram mole of a gas occupy 22.4 L under all conditions of temperature and pressure ?

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14. What is the basic difference between empirical and molecular formulae ?

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15. The percentages of all the elements present in a compound are 92. What does it indicate ?

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16. Whay is it necessary to balance a chemical equation ?

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17. In the combustion of methane, why is methane regarded s the limiting reactant ?

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18. Distinguish between molarity and molality.

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19. Is the number of molecules in one mole of a gas at `100^(@)C` and 500 mm pressure equal to or less

than the Avogadro's number ?

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20. Are 0.5 mole of NaOH and 0.5 M of NaOH solution same ?

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21. The average atomic mass of chlorine is 35.5 u. Do we come across a sample of the element with atomic

mass 35.5 u ?

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22. Out of 1 M `H_(2)SO_(4)` and 1 N `H_(2)SO_(4)`, which is more concentrated and why ?

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23. Why is the value of Avogadro's number `6.022 xx 10^(23)` and not any other value ?

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24. We breathe in fresh air in the morning walk is it pure as well ?

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25. Are the atomic masses of the elements their actual masses ?

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26. What do you understand by stoichiometric coefficients in a chemical equation ?

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27. Why is limiting reactant so named ?

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28. Are the atomic masses of some elements actually fractional ?

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29. Whay is air not always regarded as homogeneous mixture ?

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30. Hydrogen catches fire easily and oxygen helps in combusion. Why is water used for extinguishing fire ?

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31. Statements gives below pertain either to an element or mixture or compound. Identify the statement

which corresponds to (a) and (b) mixture (c) compound.

(i) The properties of the reactants are entirely different from the properties of the products of their chemical

reactions.

(ii) The constituents retain their individual chemical identify

(iii) The pure substance which cannot be subdivided into two or more substances by any chemical means.

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32. What is an atom according to Dalton's Atomic theory ?

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33. What is the effect of temperature on molarity of a solution?

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34. What is the significant of N/10 NaOH solution ?

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35. Does HCl solution have same value of molarity and normality ?

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36. In the combustion of methane, why is methane regarded s the limiting reactant ?

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37. 32 g of sulphur will react with 32 g of oxygen, even if more than 32 g of sulphur is available. Which law

of chemical combination does it illustrate ?

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38. Is law of conservation of mass always valid ?

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39. Give an example of a molecule in which the ratio of the molecular formula is six times the empirical

formula.

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40. What are the `SI` unit of molarity ?

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41. How are 0.5 m of NaOH different from 0.5 M of NaOH ?

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42. What is the difference between 0.05 g and `5.0 xx 10^(-3)g` ?

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43. Are the molar volumes of `CO_(2) and SO_(2)` different ?

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44. It the atomic masses of C and S are 12 and 32 respectively, then atom of S is how many times heavier

than an atom of carbon ?

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45. How many oxygen are present in 96 g of ozone ?

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46. Which law of chemical combination is not explained by the Dalton's atomic theory ?

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High order thinking

47. Do two moles of `N_(3)` and two moles N represent the same quantity ?

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48. Calculate molecular mass of glucose

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49. What is the difference between 0.006 g and `6.00 xx 10^(-3)g` ?

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1. Five grams of `KCIO_(3)` yield `3.041 g` of `KCI` and `1.36 L` of oxygen at standard temperature and

pressure. Show that these figures support the law of conservation of mass within limits of `+- 0.4 %` error.

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2. Benzene, ethane and ethylene belong to the family of hydrocarbons. Show how the data given below is in

consistent with the law of Multiple Proportions.

`{:("Compound",underset("in 5.0 g of the sample")("Mass of carbon"),underset("in 5.0 g of the sample")

("Mass of hydrogen")),("Benzene","4.61 g","0.39 g"),("Ethane","4.00 g","1.00 g"),("Ethylene","4.29 g","0.71

g"):}` .

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3. How many years it would take to spend Avogadro's number of rupees at the rate of 10 lakh rupees per

second?

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4. The vapour density of a mixture containing `NO_(2)` and `N_(2)O_(4)` is `38.3 at 27^(@)C`. Calculate the

mole of `NO_(2)` in `100 g` mixture.

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5. A mixture of formic acid and oxalic acid is heated with conc. `H_2SO_4` . The gas produced is collected

and treated with `KOH` solution where the volume decreases by 1/6th. The molar ratio of two acids (formic

acid/oxalic acid) in the original mixuture is:

(a) `4:1`

(b) `1:4`

(c) `2:1`

(d) `1:2`

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6. An alloy of iron (53.6 %), nickel (45.8 %) and maganese (0.6 %) has a density of `8.17 "g cm"^(-3)`.

Calculate the number of Ni atoms present in the alloy of dimensions `10.0 cm xx 20.0 cm xx 15.0 cm`.

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7. On heating `1.763 g` of hydrated `BaCl_(2)` to dryness, `1.505 g` of anhyrous salt remained, What is the

formula of hydrate?

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8. The general formula of a carbohydrate is `C_(x)(H_(2)O)_(y)`. 3.1 g of the carbohydrate on heating in the

absence of oxygen yields 1.24 g of carbon. The molecular mass of carbohydrate is 180u. Calculate its

molecular formula.

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9. Carbohydrates are compounds containing only carbon, hydrogen and oxygen having the atomic ratio of

`H : O` as `2 : 1`. When heated in the absence of air, these compounds decompose to form carbon and

water.

a. If `310 g` of a carbohydrates leaves a residue of `124 g` of carbon on heating in absence of air, what is

the empirical formula of the carbohydrate?

b. If 0.0833 mole of the carbohydrate contains `1.0 g` hydrogen , what is the molecular formula of the

carbohydrate?

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10. Zinc and hydrochloric acid react according to the reaction:

`Zn_((s))+2HCl_((aq.))rarr ZnCl_(2(aq.))+H_(2(g))`

If `0.30` mole of `Zn` are added to hydrochloric acid containing `0.52` mole `HCl`, how many moles of

`H_(2)` are produced?

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11. A solid mixture `5 g` consists of lead nitrate and sodium nitrate was heated below `600^(@)C` until

weight of residue was constant. If the loss in weight is `28%` find the amount of lead nitrate and sodium

nitrate in mixture.

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12. Commercially available concentrated hydrochloric acid contains 38 % HCl by mass. (i) What is the

molarity of the solution if its density is `1.19 "g cm"^(-2)` ?

(ii) What volume of concentrated HCl is needed to make 1.0 L of 0.2 M HCl solution ?

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13. Calculate the volume of `1.00 mol L^(-1)` aqueous sodium hydroxide that is neutralized by `200 mL` of

`2.00 mol L^(-1)` aqueous hydrochloric acid and the mass of sodium chloride produced. Neutralization

reaction is,

`NaOH_((aq.))+HCl_((aq.))rarr NaCl_((aq.))+H_(2)O_((l))`

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14. 1.2 g mixture of `Na_(2)CO_(3) and K_(2)CO_(3)` was dissolved in water to form `100 cm^(3)` of the

solution. `20 cm^(3)` of this solution required `40 cm6(3)` of 0.1 N HCl solution for neutralisation. Calculate

the percentage composition of the mixture.

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15. How many millilitres of 0.5 M `H_(2)SO_(4)` are needed to dissolve 0.5 g of copper (II) Carbonate ?

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16. Calculate the density `("in gm L"^(-1))` of a 3.60 M sulphuric acid solution that is 29 % `H_(2)SO_(4)` by

mass `("molar mass = 98 g mol"^(-1))`

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17. One litre of a solution of N/2 HCl was heated in beaker and it was observed that when the volume of

solution got reduce to 600 mL, 3.25 g of HCl was lost. Calculate the normality of the resulting solution.

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18. `50 cm^(3)` of 0.2 N HCl is titrated against 0.1 N NaOH solution. The titration is discontinued after

adding `50 cm^(3)` of NaOH solution. The remaining titration is completed by adding 0.5 N KOH solution.

What is the volume of KOH required for completing the titration ?

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Value Based

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19. How many `mL` of a `0.1M HCl` are required to react completely with `1 g` mixture of `Na_(2)CO_(3)`

and `NaHCO_(3)` containing equimolar amounts of two?

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1. A student was asked by his teacher to verify the law of conservation of mass in the laboratory. He

prepared 5 % aqueous solutions of NaCl and `Na_(2)SO_(4)`. He mixied 10 mL of both these solutions in a

conical flask. He weighed the flask on a balance. He then stirred the flask with a rod and weighed it after

sometime. There was no change in mass. Read this narration and answer the following question

(i) Was the student able to verify the law of conservation of mass ?

(ii) If not, what was the mixtake committed by him ?

(iii) In your opinion, what he should have done ?

(iv) What is the value associated with it ?

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2. A student collected three samples of water from different sources and found out the percentage of

hydrogen and oxygen by mass in thse samples. It should have been 1 : 8 by mass. But it was different in all

three samples, Moreover, the values did not match

(i) In your opinion why did the student get different results for different samples ?

(ii) What should have been done by him ?

(iii) Which law of chemical combination is supported by these observations

(iv) How will you check the purity of water in the laboratory ?

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3. Mole concept is an important tool for dealing with chemical calculations. The element have atomic mases

while compounds have molecular masses or molar masses. Mole is infact, a collection of Avogadro's

number `(N_(A))` of the particles of a substance whether element or compound. The value of Avogadro's

number is `6.022 xx 10^(23)`

(a) Why is mole commonly called chemist's dozen ?

(b) What is the value associated with the term mole ?

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4. Modern era is a machine era and there is hardly any scope of physical expresion or exercise. Life has

become very stressful since we have become very ambitious. Under the circumstances, our body has

become more prone to disease. Diabetes is a very common disease from which millions are siffering

throughout the world. Artificial sweeteners have replaced sugar which is a traditional sweetener.

(i) What is the chemical name and nature of sugar ?

(ii) What is the harm of consuming sugar in excess ?

(iii) In what way artificial sweeteners are better ?

(iv) Name any three artificial sweeteners which are used these days.

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5. One of the major gift of modern civilisation is the stress. In the mad race to earn more money and the buy

more comforts, we have added stress to our life. We donot have proper sleep and this leads to many

disorders and diseases. We have to take sleeping pills from time to time

(i) What is the chemical name of the sleeping pills ?

(ii) How do they help in reducing stress ?

(iii) What is the value associated with these ?

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