Waec Chemistry 1998 Past Questions and Answers

Question 11:

• WAEC 1998

Pipe-borne water is usually chlorinated in order to

A. Improve the teste of the water
B. Remove the hardness in the water clear
C. Coagulate sediments in the water
D. Kill harmful bacteria in the water
E. Make the water clear and colourless

Question 12:

• WAEC 1998

Which of the following can be added to dissolve the precipitate formed in the reaction represented by the following equation? CaCl_2(aq) + H₂C₂O _4(s) ⇌ CaC ₂O₂

A. Calcium chloride solution
B. Concentrated hydrochloric acid
C. Ethanol
D. Ethanedioc acid
E. Aqueous ammonia

Question 13:

• WAEC 1998

The spontaneity of a chemical reaction is determined by the change in the

A. Concentration of the reactants
B. Temperature of the system
C. Free energy of the system
D. Pressure applied to the system
E. Volume of the reactants

Question 14:

• WAEC 1998

Two metallic ions commonly present in hard water are

A. Ca²⁺ and Zn²⁺
B. Cu²⁺ and Na⁺
C. Mg²⁺ and Ca²⁺
D. Fe²⁺ and Na⁺
E. Zn²⁺ and Cu²⁺

Question 15:

• WAEC 1998

Rusting of iron is an example of

A. Deliquescence
B. Decomposition
C. Displacement reaction
D. Redox reaction
E. Reversible reaction