JAMB Chemistry Past Questions & Answers - Page 434

2,166.

A gas jar was inverted over burning yellow phosphorus floating over water in a beaker. After burning, the water level was found to rise in the gas jar. The water level rises because

A.

pressure inside the gas jar is greater than pressure outside it

B.

the air in the gas jar had been used up by burning

C.

oxygen in the gas jar had been used up by burning

D.

nitrogen in the gas jar had been used up by burning

E.

the temperature in the jar had risen considerably

Correct answer is C

No explanation has been provided for this answer.

2,167.

In titration involving sodium hydroxide and dilute hydrochloric acid, where would you place the base?

A.

in the beaker

B.

in the conical flask

C.

in a burette

D.

in the standard flask

E.

in the measuring cylinder

Correct answer is B

Add a few drops of indicator and put the conical flask on a white tile. Fill the burette with acid and note the starting volume. Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix.

2,168.

By means of filtration, one component can be obtained pure from an aqueous mixture of sodium chloride and?

A.

potassium nitrate

B.

sand

C.

lead nitrate

D.

sugar (glucose)

E.

starch

Correct answer is B

Use enough water to completely submerge the sand-salt mixture. Stir or shake the mixture for a few minutes so that the salt dissolves in the water.

The sand is insoluble, so it will remain visible.

2,169.

Which of the following changes is physical?

A.

Adding iron filing to aerated water

B.

Adding sodium metal to water

C.

Cooling a solution of Iron (II) sulphate to obtain the hydrated salt

D.

Cooling water to obtain ice

E.

Burning the domestic gas (Utilgas) for cooking

Correct answer is D

No explanation has been provided for this answer.

2,170.

If hydrogen sulphide gas is passed into a solution of a pure iron chloride, a yellow deposit appears. If the deposit is filtered, a pale green solution is left behind. The pale green solution is

A.

dilute sulphuric acid

B.

dilute hydrochloric acid

C.

unreacted hydrogen sulphide in water

D.

iron (III) chloride

E.

Iron (II) chloride

Correct answer is E

No explanation has been provided for this answer.