WAEC Chemistry Past Questions & Answers - Page 95

471.

Iron is often galvanized in order to

A.

Make it more malleable

B.

Remove the impurities unit

C.

Protect it against corrosion

D.

Render it passive

Correct answer is C

Iron is galvanized with zinc covering to protect it against corrosion. Option A, B, D are the main reasons iron is galvanized

472.

Which of these require crystallization most?

A.

Drug making

B.

Cement making

C.

Paint making

D.

Perfume making

Correct answer is A

Crystallization is required the most in industries where the purity of their products is important e.g in the manufacture of drugs and in sugar production. Options B,C and D do not undergo crystallization

473.

The filter in the cigarette reduce the nicotine construct by

A.

burning

B.

adsorption

C.

evaporation

D.

absorption

Correct answer is B

The acetate and paper modify the particulate smoke phase by particle retention (filtration), and finely divided carbon modifies the gaseous phase (adsorption)

474.

One of the methods used for combating air pollution is

A.

burning of solid waste

B.

provision of sanitary land fills

C.

legislation against some industrial practices

D.

scavenging of refuse dumps

Correct answer is C

No explanation has been provided for this answer.

475.

Iron is often galvanized in order to

A.

make it more malleable

B.

remove the impurities in it

C.

protect it against corrosion

D.

render it passive

Correct answer is C

No explanation has been provided for this answer.