hkdse chemistry 2014 paper1a

2014-DSE-CHEM-1A-2

This section consists of two parts. There are 24 questions in PART I and 12 questions in PART II.

Choose the best answer for each question.

Candidates may refer to the Periodic Table printed on page 20 of Question-Answer Book B.

PART I

1. Which of the following substance is the main constituent of town gas?

A. hydrogen B. methane C. carbon monoxide D. gaseous naphtha

2. Element Q forms a stable Q2+ ion. What may the atomic number of Q be? .

A. 6 B. 11 C. 14 D. 20

3. The formula for ozone is O3. If one mole of ozone contains x atoms, how many atoms will atoms will one mole of oxygen gas contain?

A. x/3. B. 2x/3. C. 3x/2. D. 3x.

4. The atomic number of element X is 15. X reacts with chlorine to form a chloride. Which of the

following can represent the electronic diagram of the chloride? (Only electrons in the outermost shells are shown.)

2014-DSE-CHEM-1A-3

5. Which of the following environmental problems is NOT caused by excessive burning of fossil

fuels?

A. the corrosion of marble statues. B. the formation of smog. C. a higher incidence of liver diseases. D. global warning.

6. A detergent has the following structure:

Which of the following statements concerning the detergent is correct?

A. Its hydrocarbon chain is hydrophilic. B. It can be manufactured from vegetable. C. It is readily degraded by micro-organisms. D. It acts as an emulsifier in the cleaning process.

7. The formula of a solid dibasic acid is H2X. 2.88 g of the acid is dissolved in some distilled water and the solution is then diluted to 250.0 cm3 with distilled water . 25.0 cm3 of the diluted solution requires 16.0 cm3 of 0.40 M sodium hydroxide solution for complete neutralization. What is the molar mass of H2X.?

A. 22.5 g B. 45.0 g. C. 90.0 g. D. 180.0 g.

8. Compound X is a white solid. When X is warmed with sodium hydroxide solution, a gas is evolved which turns moist red litmus paper blue. When chloride water is added to an aqueous solution of X, a brown solution is formed. X is probably

A. ammonium bromide. B. ammonium chloride. C. sodium bromide. D. sodium chloride.

2014-DSE-CHEM-1A-4

9. When a glass of wine is left overnight, it becomes sour. Which of the following reactions is responsible for this change?

A. Fermentation. B. Oxidation. C. Dehydration. D. Esterification.

10. A zinc-carbon cell is connected to a voltmeter as shown in the below diagram.

Which of the following statements concerning the set-up is INCORRECT ?

A. electrons flow from the zinc case to the carbon rod in the external circuit. B. The zinc case gradually becomes thinner as the cell discharges. C. Manganese (Ⅳ) oxide acts as an oxidizing agent. D. Ammonium chloride acts as a reducing agent.

11. Which of the following statements concerning one mole of nitrogen gas is/are correct?

(1) It has a mass of 14.0 g. (2) It occupies the same volume as 4.0 g of helium gas at room temperature and pressure. (3) It contains 6.02 × 1023 atoms of nitrogen. (Relative atomic masses : He=4.0, N = 14.0 Avogadro constant=6.02 × 1023 mol-1)

A. (1) only. B. (2) only. C. (1) and (3) only D. (2) and (3) only

2014-DSE-CHEM-1A-5

12. A mixture contains only copper (II) oxide and anhydrous copper (II) sulphate. Which of the following methods can be used to separate copper (II) oxide from the mixture?

(1) Add water to the mixture and then filter. (2) Add dilute nitric acid to the mixture and then filter. (3) Add concentrated hydrochloric acid to the mixture and then filter.


13. Directions : Q.13 and Q.14 refer to the following experiment.

Which of the following combinations is correct?

Gas X Gas Y A. Chlorine Hydrogen B. Chlorine Oxygen C. Hydrogen Chlorine D. Oxygen Hydrogen

14. Which of the following statements concerning the above experiment is/are correct? (1) Platinum electrodes should be used. (2) The concentration of Na+ (aq) ions around the cathode increase . (3) The solution changes from colorless to pink.


2014-DSE-CHEM-1A-6

15. In Which of the following equations does the underlined substances become reduced?

A. CuSO4 + Zn → ZnSO4 + Cu B. 2 FeCl2 + Cl2 → 2FeCl3 C. Pb(OH)2 + 2HNO3 → Pb(NO3)2 + 2H2O D. MgCO3 + 2HCl → MgCl2 + CO2 + H2O

16. A student performed a titration in which he added an acid from a burette to an alkali contained in a conical flask. The following diagrams show the initial and finial readings of the burette.

What was the volume of the acid added form the burette to the conical flask?

A. 24.5 cm3. B. 24.6 cm3. C. 24.7 cm3. D, 32.3 cm3.

17. Which of the following statements concerning the reaction of aqueous ammonia with with hydrochloric acid is correct?

A. The reaction is exothermic. B. A white precipitate is formed. C. Ammonium chloride and chloride are produced. D. The product ammonium chloride is a covalent compound.

18. Metal X reacts with dilute hydrochloric acid to liberate hydrogen. But metal Y and metal Z have no reaction with the dilute acid. The oxide of metal Y decomposes on heating but the oxide of metal Z does not. Which of the following arrangements represents the order of increasing reactivity of the three metals?

A. X < Y < Z B. Y < Z < X C. X < Z < Y D. Z < Y < X

2014-DSE-CHEM-1A-7

19. Which of the following methods is NOT used to preserve food ?

A. Adding salt. B. Adding vinegar C. Adding aqueous ammonia. D. Storing at a low temperature.

20. What volume of water is required to dilute 100 cm3 of 8 M hydrochloric acid to a concentration of 2 M?

A. 200 cm3 B. 300 cm3 C. 400 cm3 D. 700 cm3

21. Which of the following statements concerning a silver oxide cell is/are correct?

(1) The cell is rechargeable. (2) The cell can maintain a steady voltage during discharge. (3) The positive electrode of the cell is silver oxide.


22. Which of the following statements concerning the contact process is/are correct?

(1) The sulphur dioxide used in the process can be produced by roasting sulphide ores. (2) A gaseous mixture of sulphur dioxide and oxygen in the mole ratio of 1 : 2 is passed

into the catalytic conversion chamber. (3) The sulphur trioxide produced is absorbed by water in the absorption tower.


2014-DSE-CHEM-1A-8

Directions: Each question below (Question Nos. 23 to 24) consists of two separate statements . Decide whether each of the two statements is true or false; if both are true, then decide whether or not the second statement is a correct explanation of first statement. Then select one option from A to D according to the following table :

A. Both statements are true and the 2 nd statement is a correct explanation of the 1 st statement. B. Both statements are true but the 2 nd statement is NOT a correct explanation of the 1 st statement. C. The 1 st statement is false but the 2 nd statement is true. D. Both statements are false.

1 st statement 2 nd statement

23. The basicity of ethanoic acid is four One molecule of ethanoic acid contains four

atoms of hydrogen

24. Huge quantities of carbon dioxide Carbon dioxide can trap the solar energy which produced by the burning of fossil is re-radiated from the earth’s surface to the fuels cau atmosphere.

2014-DSE-CHEM-1A-9

PART II 25. The formula below can be used to represent the structure of some polymers.

(X represents an atom or a group of atoms.) Which of the following combinations is INCORRECT ?

X Name of polymers

A. H Polyethene B. Cl Polyvinyl chloride C. CH3 Perspex D. C6H5 Polystyrene

26. A certain amount of silver oxide is heated in a tested tube. Which of the following graphs represents the correct plot of the mass of the contents of the test tube against time.

2014-DSE-CHEM-1A-10

27. Which of the following statements concerning the recycling of plastics are correct?

(1) The recycling of plastic can help to solve the disposal problem of plastic. (2) The recycling of plastic can save raw materials derived from petroleum. (3) It is difficult to separate different types of plastic in the recycling process.

A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1),(2) and (3)

28. Which of the following products may be formed from the cracking of heavy oil fraction?

(1) CO. (2) C2H4. (3) C8H18.


29. Which of the following are characteristics of a homologous series?

(1) Members of the series can be represented by the same general formula. (2) Members of the series have same physical properties. (3) Members of the series have similar chemical properties.


30. Which concentrated sulphuric acid is added dropwise to a solution containing urea and methanal in a test tube with shaking, a white solid can be formed. Which of the following statements about this experiment is/ are correct?

(1) The reaction involved is condensation polymerization. (2) Concentration sulphuric acid acts as an oxidizing agent. (3) The white solid is a thermoplastic substance.

A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

201

31.

32.

33.

14-DSE-CHE

. A mixthe fo

. The r

X(aq) Whictime w

. On hefollow

(1) (2) (3)

EM-1A-11

xture of amollowing gra

reaction betw

) + Y(aq) ↔

ch of the folwhen fixed

eating, bluewing statem

Heat wou On furth A chemic

A. B. C. D.

mmonia and aphs repres

ween X(aq)

↔ Z(aq)

llowing grapquantities o

e copper(II) ments are co

uld be liberer heating, tcal change o

(1) and (2) (1) and (3) (2) and (3) (1), (2) and

oxygen is pents a plot o

) and Y(aq)

phs represenof X(aq) an

sulphate crrrect?

rated if watethe white pooccurs durin

only only only

d (3)

passed over of the mass

is represen

nts the channd Y(aq) are

rystals gradu

er is added towder woulng the heati

red hot platof platinum

nted by the f

nge of concee introduced

ually chang

to the whiteld turn redding of the bl

tinum for a m against tim

following eq

entration ofd into a clos

ge to a white

e powder. dish-brown. lue crystals

few minuteme?

quation:

f Y(aq) withed containe

e powder.

.

es. Which

h er?

Which of th

of

he

2014-DSE-CHEM-1A-12

34. The following experiment on the study of the rate of reaction between hydrochloric acid and sodium thiosulphate solution:

10 cm3 portions of 2.0M hydrochloric acid were added to four separate conical flasks each containing sodium thiosulphate solution which was prepared respectively as follows:

conical flask

sodium thiosulphate solution volume of water

concentration volume W 1.0M 80 cm3 10 cm3 X 1.5M 60 cm3 30 cm3 Y 2.5M 30 cm3 60 cm3 Z 3.0M 20 cm3 70 cm3

In which of the above conical flasks does the reaction proceed at the fastest rate?

A. W B. X C. Y D. Z

Directions: Each question below (Question Nos. 23 to 24) consists of two separate statements . Decide whether each of the two statements is true or false; if both are true, then decide whether or not the second statement is a correct explanation of first statement. Then select one option from A to D according to the following table :

A. Both statements are true and the 2 nd statement is a correct explanation of the 1 st statement. B. Both statements are true but the 2 nd statement is NOT a correct explanation of the 1 st statement. C. The 1 st statement is false but the 2 nd statement is true. D. Both statements are false.

1 st statement 2 nd statement

35. Concentrated sulphuric acid can be used to Sulphuric acid is more volatile than nitric prepare nitric acid. acid

36. When car exhaust gases are bubbled into Nitrogen dioxide is present in car exhaust citrated blood, the colour of the blood gases. gradually becomes cherry red.

END OF SECTION A