chapter 14 environmental chemistry

7/30/2019 Chapter 14 Environmental Chemistry

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Environmental Chemistry TS11. Gas released during Bhopal tragedy was:

(a) Sodium isothiocyanate (b) ethyl isothiocyanate

(c) Potassium isothiocyanate (d) methyl isothiocyanate

Ans: (d)

Explanation:

Methyl isothiocyanate was the principle toxic gas responsible for Bhopal tragedy.

Chapter: Environmental Chemistry

Subtopic: Tropospheric Pollution

Difficulty Level: Easy

2. A brick kiln should not be allowed near an orchard:a) To save plants from soil erosionb) To save fruits from laborersc) To save plants from smoke and toxic gases emitted by kilnd) To save plants from transport vehiclesAns: (c)

Explanation:

SO2 gas produced from brick kiln causes death of plants.




3. Which of the following is (are) incorrect?a) The lowest region of atmosphere is known as Stratosphere.b) CO gas forms highly stable complex with blood known as carboxyhaemoglobin.c) Water vapor present in the atmosphere acts as greenhouse gas.d) Rain having pH value less than 7 is known as acid rain.Ans: (a, d)

Explanation:


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a) The lowest region of atmosphere is known as troposphere not the stratosphere.b) CO gas combines with hemoglobin present in blood to form carboxyhaemoglobin which is about

300 times more stable than oxyhaemoglobin. It reduces the oxygen carrying capacity of blood.

c) Atmospheric gases which are transparent to sunlight but not to heat radiation from earthsurface are known as greenhouse gas. Water vapor acts as greenhouse gas. Hence option (c) is

true.

d) Rain having pH value less than 5.6 is termed as acid rain. Hence option (d) is false.



Difficulty Level: Hard

4.

Which of the followings pair is (are) not present in acid raina) and b) and c) and d) and Ans: (c)

Explanation:

Acid rain is caused due to reaction of water with gaseous oxides present in atmosphere. As oxides of

C, N and S are present in the form of CO2, NOX, SO2 and SO3; their corresponding acids are present in

acid rain. But is absent.



Difficulty Level: Medium

5. Assertion (A): Classical smog occurs in cold humid climate and it is acidic as well as reducing innature.

Reason (R): It is a mixture of smoke, fog and sulphur dioxide.

a) Both A and R are correct and R is the correct explanation of A.b) Both A and R are correct but R is not the correct explanation of A.c) A is correct but R are not correct.d) A is not correct but R is correct.


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Ans: (a)

Explanation:

Classical smog occurs in cold humid climate. It is a mixture of smoke, fog and sulphur dioxide.

Presence of SO2 makes it both acid as well as reducing.




6. Which of the followings is (are) incorrect about photochemical smoga) It is produced in warm, dry and sunny climateb) It is oxidizing in nature.c)

Ozone gas is one of its constituents.

d) It is formed in stratosphere.Ans: (d)

Explanation:

Photochemical smog is formed in troposphere not in stratosphere. It is produced in warm, dry and

sunny climate. Its main constituents are and unsaturated carbons. Ozone is formed due to

reaction between and atmospheric oxygen.

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() ()

() () ()




7. Which of the following pairs is secondary precursors of photochemical smog(a) SO2 and NO2

(b) SO2

and hydrocarbons

(c) NO2 and hydrocarbons

(d) O3 and PAN

Ans: (d)

Explanation:

Photochemical smog does not contain SO2. Hence we straight away discard options (a) and (b).


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NO2 and hydrocarbons are primary precursors while O3, PAN, Formaldehyde, and Acrolein are

secondary precursor of photochemical smog.




8. The pollutants which come directly in the air from sources are called primary pollutants. Primarypollutants are sometimes converted into secondary pollutants. Which of the following is the

secondary pollutant?

(a) CO (b) PAN (c) SO2 (d) Aerosol

Ans: (b)Explanation:

PAN (Peroxyacetyl Nitrate) is secondary pollutants formed as photochemical smog by interaction of

oxides of nitrogen on hydrocarbons.




9. Ozone hole refers toa) Increased concentration of ozoneb) Reduction in the thickness of ozone layer in tropospherec) Reduction in the thickness of ozone layer in stratosphered) Hole in ozone layerAns: (c)

Explanation:

It refers to reduction in the thickness of ozone layer. As ozone layer exists in stratosphere, option (c)

is the correct answer.


Subtopic: Stratospheric Pollution



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10.CFCl3 is responsible for the decomposition of ozone layer. Which of the following reacts with ozoneto form oxygen?

(a) (b) (c) (d)

Ans: (d)

Explanation:

The free radical produced causes destruction of ozone.

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() () ()




11.Which of the following is (are) incorrect?a) Chlorofluorocarbons are responsible for ozone layer depletionb) Greenhouse effect is responsible for global warmingc) Ozone layer does not permit infrared radiation from the sun to reach the earthd) Acid rains is mostly because of oxides of nitrogen and sulphurAns: (c)

Explanation:

Ozone layer does not allow UV radiation from the sun to reach the earth.




12.Which one is not correct?Greenhouse effect:

a) Is mainly due to high concentration of CO2 in atmosphereb) Is influenced by gases such as CH4, O3 and chlorofluorocarbonsc) Would result in the warming up of the earthd) Would result in lowering the level of oceans due to high evaporationAns: (d)

Explanation:


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Greenhouse effect would cause melting of polar ice caps and glaciers that will result in increasing

the ocean levels, thereby causing submerging of low lying areas.




13.Which of the following(s) pair does not consist of greenhouse gases?a) b) c) d) Ans: (b)

Explanation:

Except CO, all other gases act as greenhouse gas.

Points to remember:




14.Assertion (A): Use of Chlorofluorocarbons (CFCs) is hazardous to environment.Reason (R): CFCs are very reactive, flammable and toxic gases.

a) Both A and R are correct and R is the correct explanation of A.b) Both A and R are correct but R is not the correct explanation of A.c) A is correct but R are not correct.d) A is not correct but R is correct.Ans: (c)

Explanation:

CFCs are responsible for responsible depletion of ozone layer. Hence it is hazardous to

environment. But they are non-reactive, non-flammable and non-toxic gases. Thats why they are

used in refrigerators.


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15. If BOD of river is high, it means that the river is:a) Not pollutedb) Very much polluted with inorganic chemicalsc) Very much polluted with organic chemicals which are decomposed by micro-organismsd) Polluted with pesticides

Ans: (c)

Explanation:

BOD is the amount of oxygen required by bacteria to break down the organic matter present incertain volume of water. High BOD means high demand for oxygen, which means high levels of

organic pollutants.


Subtopic: Water Pollution


16.Pathogens area) Bacteria and other organismsb) Pesticidesc) Organic wastesd) Chemical pollutantsAns: (d)

Explanation:

Pathogens are bacteria and other organisms which enter into water from domestic sewage and

animal excreta.

17.Which of the followings is (are) incorrect?Addition of Phosphate containing fertilizers into water causes

a) Decrease in amount of dissolved oxygen in water.b) Eutrophicationc) Increase in fish population


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d) Enhanced growth of algaeAns: (c)

Explanation:

Addition of phosphates in water enhances algae growth. Such profuse growth of algae covers the

water surface and reduces the oxygen concentration in water. It inhibits the growth of living

organisms such as fish in water. This process of loss of biodiversity is known as Eutrophication.

Hence only option (c) is incorrect.




18.Excess of which of the followings in drinking water is responsible for disease known as Blue BabySyndromeor Methemoglobinemia?

a) b) c) d)

Ans: (b)

Explanation:

The disease Blue Baby Syndrome or Methemoglobinemia is caused due to presence of excess

ion in drinking water.




19.What is DDT among the followinga) Greenhouse gasb) A fertilizerc) Biodegradable pollutantd) Non-biodegradable pollutantAns: (d)

Explanation:


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DDT is a non-biodegradable pollutant


Subtopic: Soil Pollution


20.Green chemistry means such reactions which:(a) Are related to the depletion of ozone layer

(b) Produce colour during reactions

(c) Study the reactions in plants

(d) Reduce the use and production of hazardous chemicals

Ans: (d)

Explanation:Green chemistry is the study of science dealing with development of environment friendly

technology. Hence option (d) is correct.


Subtopic: Green Chemistry


chapter 14 environmental chemistry

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