WAEC Past Questions and Answers - Page 1662

8,306.

Rusting of iron is an example of

A.

deliquescence

B.

decomposition

C.

displacement reaction

D.

redox reaction

E.

reversible reaction

Correct answer is D

No explanation has been provided for this answer.

8,307.

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+

Correct answer is C

No explanation has been provided for this answer.

8,308.

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

Correct answer is C

No explanation has been provided for this answer.

8,309.

Which of the following can be added to dissolve the precipitate formed in the reaction represented by the following equation? CaCl2(aq) + H2C2O 4(s) ⇌ CaC 2O2

A.

Calcium chloride solution

B.

Concentrated hydrochloric acid

C.

Ethanol

D.

Ethanedioc acid

E.

Aqueous ammonia

Correct answer is E

No explanation has been provided for this answer.

8,310.

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

Correct answer is D

No explanation has been provided for this answer.