WAEC Chemistry Past Questions & Answers - Page 54

266.

In a saturated solution at a given temperature, the undissolved solutes are in equilibrium with

A.

the solvent

B.

dissolved solute particles

C.

the saturated solution

D.

insoluble solute particles

Correct answer is C

A solution that is in equilibrium with undissolved solute is said to be saturated.

267.

Graphite and Diamond are similar in that they

A.

have octahedral shape

B.

have same density

C.

form carbon(IV) oxide on combustion

D.

conduct electricity

Correct answer is C

A diamond is pure carbon. Graphite is pure carbon. Both will burn to form carbon dioxide.

268.

A 0.1\(moldm^{-3}\) solution of sodium hydroxide was diluted with distilled water to 0.001\(moldm^{-3}\). What is the dilution factor?

A.

1000.00

B.

100.00

C.

10.00

D.

0.01

Correct answer is D

Dilution factor = \(\frac{molar conc. of diluted}{molar conc. of undiluted}\)

= \(\frac{0.001}{0.1} = 0.01\)

269.

Which of the following statements about endothermic reaction is correct?

A.

Activation energy is high

B.

A catalyst is required

C.

It occurs reversibly

D.

Heat energy is absorbed

Correct answer is D

Endothermic reactions are those reactions which absorb energy from the surroundings and result in a net decrease in temperature.

270.

The use of diamond in abrasives is due to its

A.

high melting point

B.

hardness

C.

octahedral shape

D.

durability

Correct answer is B

Diamonds are very hard, they are often used as an abrasive.