WAEC Chemistry Past Questions & Answers - Page 94

466.

A small quantity of solid ammonium chloride (NH4Cl) heated gently in a test tube, the solid gradually disappear produce two gases. Later, a white cloudy deposit was absence on the cooler part of the test tube. The ammonium chloride is to have undergo

A.

distillation

B.

sublimation

C.

precipitation

D.

evaporation

Correct answer is B

Sublimation is the transformation of solid gaseous state without passing through the liquid state. Options A,C,D do not show case these character of sublimation as they do not bye pass states. They are in a particular order

467.

The acid in electrolysis of water is dilute

A.

HNO3

B.

CH3COOH

C.

H2SO4

D.

HCl

Correct answer is C

HeSO4 is the acid used in the electrolysis of water. Option A,B,D are concentrated acid and they will react with the water

468.

Vulcanization involve the removal of

A.

monometer

B.

the single bond

C.

the double bond

D.

a polymer

Correct answer is C

Vulcanizer is the removal of double bend in a chemical reaction. Option A,B,D can not be removed by vulcanizer

469.

The gas that is most useful in protecting humans against solar marathon is

A.

chlorine

B.

ozone

C.

carbon IV oxide

D.

hydrogen sulphide

Correct answer is B

The ozone layer or ozone shield refers to a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet (UV) radiation. It contains high concentrations of ozone (O3) relative to other parts of the atmosphere, although still very small relative to other gases in the stratosphere

470.

In the industrial production of H2 from water gas the CO2 produced along with the H2 is removed by

A.

washing under pressure

B.

drying over phosphorus (V) oxide

C.

passing the mixture to the limewater

D.

using ammonical copper (I) chlorine

Correct answer is A

Washing under pressure is an action in the industrial production of H. Options B,C,D will not yield Co and H