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CHEMISTRY (Objective Questions And Answers)


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THEORY QUESTIONS
WAEC SYLLABUS

WASSCE 2012

Objectives



1. The number of orbitals in a p-sub level of an atom is

A. 2

B. 3

C. 5

D. 6


2. Which of the following electron configurations repres that of an atom in its ground state?

A 1 s2 2s2 2p6 3s1 3p1

B. 1 s2 2s1 2p1

C. 1s22s12p2

D. 1s22s22p63s°


3. A beam of particles was passed between charged plates as illustrated in the diagram below/ X, Y and Z are respectively





A. electron, neutron and proton

B. electron, proton and neutron

C. proton, neutron and electron

D. proton, electron and neutron.


4. Which of the following ions has an electron configuration different from the others?

A. 17CI-

B. 802-

C. 12Mg2+

D. 13AI3+


5. The atomic radii of metals are usually

A. greater than their ionic radii

B. equal to their ionic radii

C. less than their ionic radii

D. less than those of non-metals in the same period.


ANSWERS

6. Two elements, X and Y are in the same group on the periodic table because they both have the same

A. number of electronic shells.

B. number of valence electrons

C. atomic size

D. atomic numb


7. The d-block elements are paramagnetic because they

A. contain paired electrons which are repelled by magnetic field.

B. contain unpaired electrons in the partially filled 3c/-or'

C. form coloured complex ions that attract magnetic lines of force

D. have delocalized valence electrons.


8. Which of the following statements about a radioactive substance is/are correct? I. It emits radiation continuously and spontaneously. II. The emitted radiations are affected by temperature and pressure. III. The radiation can penetrate opaque matter.

A. II only

B. I and II only

C. I and III only

D. II and III only


9. Which of the following elements is a metalloid?

A. Carbon

B. Oxygen

C. Silicon

D. Sodi


10. Which of the following halogens is liquid at room temperature?

A. Chlorine

B. Fluorine

C. Iodine

D. Bromine


ANSWERS

11. The shape of a graphite crystal is

A. tetrahedral

B. pyramidal

C. hexagonal

D. octahedral


12. The compound formed by the combination of two elements with a large electronegativity difference is likely to be

A. polar covalent

B. giant molecular

C. covalent

D. ionic


13. The complex compound formed when aluminium dissolves in aqueous sodium hydroxide is

A. Na3AI(OH)4

B. NaAI(OH)4

C. NaAI(OH)3

D. Na2AI(OH)3


14. The vapour pressure of a liquid depends on I. temperature II. rate of condensation III. cohesive forces holding the particles together.

A. I only

B.I and II only

C. I and III only

D. II and III only


15. MgO does not readily dissolve in water because

A. of its high melting point

B. it is a covalent compound

C. it forms a hydroxide when dissolved in water

D. Its lattice energy is higher than its hydration energy equation.


ANSWERS

16. Consider the following reaction equation. CaCO3(s) + 2HCI(aq) CaCI2(aq) + H2O(1) + CO2(g) What mass of CaCI2 would be obtained when 25.0 g of CaCO3(s) is reacted with excess HCI(aq)? [CaCO3 = 100: CaCI2= 111]

A. 4.00Gg

B. 4.44g

C. 18.9 g

D. 27.8 g


17. The number of sulphur atoms in 3.20 g of S02(g) is [0 = 16.0 S = 32.0 Avogadro c 6.02 x 1023]

A. 3.01 X 1022

B. 6.02 x 1022

C. 6.02 X 1023

D. 1.20 x 1024


18. Consider the reaction represented by the following equation: xCH3OH + yO2 2C02+ zH20 The values of x, y and z respectively, are

A. 2, 3 and 4

B. 2, 4 and 3

C. 1, 2 and 3

D. 1, 3 and 5


19. The formula of mercury (I) dioxonitrate (III) is

A. HgNO3

B. Hg2NO2

C. Hg2(N02)2

D. Hg(N03)2


20. A sample of a gas may be identified as chlorine if it turns

A. damp blue litmus paper red

B. line water milky

C. lead ethanoate paper black

D. starch iodide paper blue – black


ANSWERS

21. A metal M forms two types of chlorine, MCI2 and MCI3. Which of the following laws best explains the relationship Between the chlorides? Law of

A. Conservation of mass

B. definite proportion

C. Multiple Proportion

D. reciprocal proportion


22. Which of the following metals would readily displace Hydrogen from steam?

A. Copper

B. Lead

C. Magnesium

D Silver


23. The volume occupied by 0.4 g of hydrogen gas s.t.p is [H = 1.00 Molar volume at s.t.p. = 22.4 dm]

A. 2.24 dm3

B. 4.48 dm3

C. 22.4 dm3

D. 44.8 dm3


24. When a substance changes directly from the gaseous state to the solid state without forming a liquid, the substance is

A. Condense

B. evaporate

C. Sublime

D. precipitate


25. At ordinary temperature directly while H2O is a liquid while H2S is a gas. This is because H20 has

A. weak intermolecular forces holding its molecules together

B. strong hydrogen bonds holding its molecules together

C. induced dipole-induced forces between its molecules.

D. ionic forces between its molecules


ANSWERS

26. The postulate that molecules are in constant random Motion best explains why liquids

A. can undergo solidification

B. maintain their volumes

C. are incompressible

D. have no characteristic shape


27. Which of the following gases has the lowest rate of diffusion under the same condition? [H = 1.00 He = 4.00 0 =16.0 : CI = 35.5]

A. CI2

B. H2

C. He

D.02


28. The energy evolved when magnesium burns in air is in the form of

A. heat

B. beat and sound

C. light and heat

D. sound


29. A substance L reacts with NH4NO3(aq) to generate ammonia gas L is likely to be

A. HCI

B. NaOH

C. CH3COOH

D. CaSO4


30. On heating, the following trioxocarbonate (IV) salts decompose to give solid residue except

A. ammonium trioxocarbonate (IV)

B. calcium trioxocarbonate (IV)

C. lead (II) trioxocarbonate (IV)

D. zinc trioxocarbonate (IV)


ANSWERS

31. Which of the following Ph values indicates that a strong base?

A. 1

B. 5

C. 9

D. 13


32. The hydrolysis of NH4CI given

A. an acidic solution

B. an alkaline solution

C. a buffer solution

D. a neutral solution.


33. A spot of oil paint on a shirt can best be removed using

A. brine

B. detergent

C. kerosene

D. warn water


Consider the following solubility curves





34. Which of the following deductions could be correctly made from the graph?

A. The solubility of U is not affected by change in temperature

B. The solubility of S decreases with increasing temperature

C. T is most soluble among the salts

D. S is least soluble among the salts


35. Consider the reaction represented by the following equation: CuO(s) + H2S04(aq) CuS04(aq) + U20(1) Which of the following factors will not affect the rate of the reaction

A. Particle size of CuO(S)

B. Concentration of H2S04(aq)

C. Temperature of the reacting mixture

D. Pressure of reaction system


Use the following graph to answer questions 36 and 37.




ANSWERS

36. The activation energy for the reaction is

A. 40 kJ

B. 60 kJ

C. 80 kJ

D. 120 kJ


37. The type of reaction represented by the graph is

A. endothermic

B. exothermic

C. catalytic

D. spontaneous


38. Which of the following devices function on redox reaction? I. Dry cell II. Car battery III. Electric generator

A. I and III only

B. II and III only

C. I and II only

D. I, II and III


39. The oxidation number of Fe in [Fe (CN)6]3- is

A. + 3

B. + 2

C. -2

D. -3


40. Consider the following reaction equation: C16H34 ---------> C5H12 + C11H22 The process represented by the equation is

A. cracking

B. fermentation

C. polymerization

D. reforming


ANSWERS



41. Consider the above structures of organic compounds, Which of the following statements about the structure is not correct? They

A. are geometric isomers

B. are saturated hydrocarbons

C. have similar physical properties

D. are members of the same homologous series


42. Which of the following substances would not produce ethanol when fermented?

A. Cane sugar

B. Glucose

C. Starch

D. Vinegar


43. An alkanol can be prepared by the reaction of an alkene with

A. concentrated tetraoxosulphate (VI) acid

B. bromine in tetrachloroethane

C. aqueous potassium tetraoxomanganate (VII)

D. sodium hydroxide solution


44. A compound contains 7.75% hydrogen, 37.21% carbon and 55.04% chlorine. Determine the empirical formula of the compound [H=1.00 C = 12.0 CI = 35.5]

A. C3H3CI

B. C2H5CI

C. C3H8CI

D. C5H2CI


45. A tertiary alkanol has a molecular formula C4H10O. What is the structural formula of the compound?

A. (CH3)2CHCH2OH

B. CH3CH2CH (OH) CH3

C. (CH3)3COH

D. CH3CH2CH2CH2OH


ANSWERS

46. Which of the following industrial processes depends on the action of enzymes?

A. Liquefaction of air

B. Manufacture of soap

C. Brewing of beer

D. Cataleptic cracking


47. Which of the following pollutants is not usually recycled?

A. Alluminium cans

B. Glass bottles

C. Nuclear wastes

D. Paper wastes


48. A metal that is widely used in the manufacture of paints 'and overhead electric cables is

A. alluminium

B. copper

C. iron

D. lead


49. Brass is a mixture of

A. Cu and Sn

B. Cu and Zn

C. Cu and Mg

D. Cu and Pb


50. Which of the following substances is mainly responsible for the depletion of the ozone layer?

A. Oxygen

B. Chlorofluorocarbon

C. Carbon(ll)oxide

D. Nitrogen (II) oxide



WASSCE JUNE 2012 CHEMISTRY OBJECTIVE TEST

ANSWERS

​1. B 2. D 3. C 4. A 4. A 6. B 7. B 8. C 9. C 10.D

11. C 12. D 13. B 14. B 15. D 16. D 17. A 18. A

19. 20. D 21. C 22. C 23. B 24. C 25. B 26.B

27. A 28. C 29. B 30. A 31. D 32. A 33. C 34. A

35. D 36. A 37. B 38. C 39. A 40. A 41. B 42. D

43. A 44. B 45. C 46. C 47. C 48. A 49. B 50. B


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