WAEC Chemistry Past Questions & Answers - Page 71

351.

A change in the temperature of a saturated solution disturbs the equilibrium between the

A.

Undissolved solute and the solvent

B.

Dissolved solute and the solvent

C.

Dissolved solute and the undissolved solute

D.

Dissolved solute and the solution

Correct answer is C

No explanation has been provided for this answer.

352.

A substance which dissolves readily in organic solvent would

A.

Be a covalent compound

B.

Have strong electrostatic forces of attraction

C.

have a high melting point

D.

Conduct electricity in molten state

Correct answer is A

No explanation has been provided for this answer.

353.

Which of the following compounds is the least soluble in water?

A.

CaCl2

B.

CaSO4

C.

NaCl

D.

Na2SO4

Correct answer is B

No explanation has been provided for this answer.

354.

Solubility is practically applied in

A.

Fractional distillation

B.

The determination of pH

C.

The determination of saturation in hydrocarbons

D.

Solvent extraction

Correct answer is D

No explanation has been provided for this answer.

355.

Which of the following oxides can be reduced by hydrogen?

A.

Aluminium oxide

B.

Magnesium oxide

C.

Sodium oxide

D.

Silver oxide

Correct answer is D

Considering the electrochemical series, we can say that hydrogen can reduce only oxides of copper, mercury, silver, and gold as these metals are less reactive than hydrogen. The reduction of oxides of tin, iron, zinc, magnesium, calcium, and potassium is not possible by hydrogen as these metals are more reactive than hydrogen