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CHEMISTRY (Objective Questions And Answers)


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THEORY QUESTIONS
WAEC SYLLABUS

WASSCE 2019

Objectives



1. The periodic table is an arrangement of elements according to their

A. oxidation number

B. atomic number

C. mass number

D. number of neutrons


2. A solid substance with high melting and boiling points is likely to be

A. a covalent compound

B. a dative covalent compound

C. an electrovalent compound

D. a non – metal


3. Which of the following metals reacts slowly with cold water?

A. Iron

B. Silver

C. Calcium

D. Potassium


4. Which of the following elements has the highest ionization energy?

A. Calcium

B. Chlorine

C. Fluorine

D. Magnesium


5. The bleaching action of chlorine is through the process of

A. hydration

B. hydrolysis

C. reduction

D. oxidation


ANSWERS

6. If 6.5g of magnesium ribbon reacts completely with hydrochloric acid, how many grams of hydrogen gas would be liberated? Mg(s) + 2HCl(aq) ⟶ MgCl2(aq) + H2(g) [H = 1.0, Mg = 24.0]

A. 0.54g

B. 0.70g

C. 1.08g

D. 1.40g


7. Calcium and magnesium belong to the same group of the periodic table because both

A. are metals.

B. form caution

C. form colorless salt

D. has same number of valence electron


8. Which of the following substances is non-polar?

A. Br

B. NH3

C. H2O

D. HBr


9. Which of the following pairs of components have the same molecular mass? [H = 1.0, C = 12.0 O = 16]

A. Ethene and ethyne

B. Ethane and ethane

C. Carbon II oxide and ethene

D. Carbon (IV) oxide and ethane


10. When equilibrium is established between dissolved and undissolve solutes, the solution is said to be

A. saturated.

B. unsaturated

C. concentrated

D. dilute


ANSWERS

11. How many moles of carbon (IV) oxide contain 16.0g of oxygen?

A. 0.20 mol

B. 0.25 mol

C. 0. 40 mol

D. 0.50 mol


12. Stiochiometry is based on the law of

A. multiple proportion

B. constant composition

C. conservation of energy

D. conservation mass


13. What is the percentage by mass of hydrogen in CH3COOH? [ CH3COOH = 60]

A. 1.7%

B. 5.0%

C. 6.7%

D. 7.1 %


14. Which of the following compounds has coordinate bond in its structure?

A. Al2Cl6

B. MgCl2

C. AgCl

D. NaCl


15. The name of the compound CH3C(CH3)2CH2CH3 is

A. 2 – methyl butane

B. 2, 2 – dimethyl butane.

C. 2 – methyl pentane

D. 2, 2- dimethyl pentane


ANSWERS

16. The properties of good primary standard include the following except

A. high molecular mass

B. low molecular mass

C. high degree of purity

D. readily available


17. What is the solubility of a salt X at 250C if the saturate solution of the salt contains 0.28g in 100cm3 of solution? [ X = 56.0g]

A. 0.0 mol dm-3

B. 0.10 mol dm-3

C. 2.60 mol dm-3

D. 2.80 mol dm-3


18. Vinegar is an aqueous solution of

A. hydrochloric acid

B. ethanedoic acid

C. ethanoic acid

D. hydrofluorine acid


19. Which of the following solution containing one mole per dm3 of the compound would have the lowest pH?

A. Ethanoic acid

B. Hydrochloric acid

C. Sodium chloride

D. Sodium hydrogentrioxoccarbonate


20. A sample of air was bubbled into water. The pH of the water slowly changed from 7 to 6. Which of the following gases in the sample caused the change?

A. Carbon (IV) oxide

B. Carbon (II) oxide

C. Nitrogen

D. Oxygen


ANSWERS

21. The most suitable indicator for the reaction between NaOH(aq) and HCOOH(aq) is

A. bromocresol

B. methyl orange

C. methyl red

D. phenolphthalein


22. Consider the following reaction equation: 2Al(OH)3 + 3H2SO4 ⟶ Al2(SO4) + 6H2O. How many moles of tetraoxosulphate (VI) acid is needed to produce 0.5 ml of aluminium tetraoxosulphate (VI)?

A. 0.5

B. 1.0

C. 1.5

D. 3.0


23. Which of the following of substances has the highest heat of neutralization?

A. Strong acid and strong base

B. Weak acid and weak base

C. Strong acid and weak base

D. Weak acid and strong base


24. When quicklime dissolves in water,

A. heat is absorbed

B. heat is evolved

C. oxygen liberated

D. hydrogen is given off.


25. If the value of ∆H is positive for a reaction, it means that the reaction is

A. exothermic

B. endothermic

C. spontaneous

D. slow


ANSWERS

26. Which of the following compound is formed by the oxidation of ethanol?

A. C2H4CO2H

B. C2H5CO2H

C. CH3OH

D. CH3CO2H


27. What is the characteristic of the gas liberated when dilute hydrochloric acid is added to iron (II) sulphide?

A. Turns lime water milky

B. Decolorized bromine water

C. Gives a pop sound

D. Turns lead (II) ethanoate paper black


28. An organic compound contains 72% carbon, 12% hydrogen and 16% oxygen by mass. What is the empirical formula of the compound? [H = 1.0, C = 12.0, O = 16.0]

A. C3H8O

B. C6H12O

C. C6H12O2

D. C12H12 O11


29. When excess chlorine is mixed with ethane at room temperature, the product formed is

A. 1, 2 – dichloroethane

B. 1, 2 dichlorethene

C. 1, 1 – dichloroethane

D. 1, 1 chloroethene


30. W\hich of the following reagents could be used to distinguish between propan – 1 –ol and propan -2-ol?

A. H +/K2Cr2O7

B. I2OH.

C. CH3COOH

D. NaCl


ANSWERS

31. If a catalyst s added to a system at equilibrium and the temperature and pressure remain constant, there would be no effect on the

A. activities energy of the reaction

B. rate of the forward reaction

C. rate of the reverse reaction

D. heat of reaction


32. Consider the following reaction equation: 3Cl2 + 2NH3 ⟶ N2 + 6HCl. NH3 is acting as

A. a reducing agent

B. a dehydrating agent

C. a drying agent

D. an oxidizing agent


33. The oxidation number of chromium in Cr2O7 is

A. +4

B. +5

C. + 6

D. +7


34. The process by which alkanoic acid reacts reversibly with alkanols is known as

A. saponification

B. esterification

C. carboxylation

D. halogenations


35. If the oxidation potential of Mg and Al are +2.3 7 volts and + 1.66 volts respectively, then Mg would

A. not replace Al

B. be replaced by Al

C. remain in the solution

D. replace Al


ANSWERS

36. Consider the reaction represented by the following equation: 2SO2(aq) + O2(g) ⇌ 2SO3(aq).

A decrease in pressure of the reaction would A. decrease the concentration of SO2

B. have no effect on the reaction.

C. shift the equilibrium position to the left.

D. shift the equilibrium position to the right.


37. In a mixture of gases which do not react chemically together, the pressure of the individual gas is

A. atmosphere pressure

B. vapor pressure.

C. total pressure

D. partial pressure


38. Biotechnology is applied in the

A. treatment of sewage

B. treatment of water

C. purification of chemicals

D. purification of metals


39. Which of the following organic compound has the lowest boiling point?

A. C6H14

B. C5H12

C. C4H10

D. (CH3)3CH


40. Consider the reaction represented by the following equation: C2H2 - H2 X H2 ⟶ Y. X and Y respectively are

A. ethane and ethane

B. ethane and ethane

C. ethyne and ethane

D. ethane and ethyne


ANSWERS

41. Which of the following substances can be classified as heavy chemical?

A. CaOCl2.

B. H2SO4.

C. AgNO3

D. CaO


42. In Boyle’s law,

A. T is constant, while P varies directly with V.

B. P is constant, while V varies inversely with T.

C. V is constant, while P varies directly with T.

D. T is constant, while V varies inversely with P.


43. Which of the following apparatus is not used in volumetric analysis?

A. Pipette

B. Burrete

C. Desiccator

D. Conical flask


44. One of the deduction from Rutherford’s alpha particle scattering experiment is that

A. electron are negatively charged

B. electron have negligible mass

C. nuclei of atom are positively charged

D. protons are positively charged


45. The atoms 64/29 Cu and 65/30 Zn have the same number of

A. nucleon

B. electrons

C. neutrons

D. protons


ANSWERS

46. The number of electrons in the 3d orbital of 24Cr is

A. 2.

B. 3.

C. 4.

D. 5.


47. The method used collect a gas in the laboratory depends on its I. boiling point. II. density III. smell. IV. Solubility in water.

A. I and II only

B. II and IV only

C. III and IV only

D. I, II, III and IV


48. Which of the following method is not used for the separation of mixtures?

A. Chromatography

B. Crystallization

C. Distillation

D. Electrolysis


49. The group to which element belong in the periodic table is determined by the number of

A. electrons

B. core electrons

C. valence shells

D. valence electron


50. Kipps apparatus can be used to prepare

A. H2

B. NH3

C. O2

D. H2S



WASSCE JUNE 2019 CHEMISTRY OBJECTIVE TEST

ANSWERS

​1. B 2. C 3. A 4. D 5. D 6. A 7. D 8. C 9. C

11. D 12. D 13. C 14. A 15. D 16. C 17. A 18. C 19. A 20. B

21. D 22. C 23. A 24. B 25. B 26. D 27. D 28. B 29. A 30. A

31. D 32. A 33. C 34. B 35. D 36. C 37. D 38. A 39. B 40.

41. B 42. D 43. C 44. D 45. C 46. C 47. D 48. D 49. D 50. D


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