JAMB Chemistry Past Questions & Answers - Page 107

531.

The substance that is used in the steel industry for the removal of carbon. Sulphur and phosphorus impurities from pig iron is

A.

oxygen

B.

chlorine

C.

nitrogen

D.

hydrogen

Correct answer is A

Oxygen is a substance that is used to remove impurities from pig iron. Options B, C, D will be effective in removing impurities positive]

532.

In countries where the temperature fall below 273k, salt always spilled on the road in order to

A.

increase the boiling point

B.

increase the density of the ice

C.

make the ice impure

D.

reduce the freezing point of ice

Correct answer is D

No explanation has been provided for this answer.

533.

Alloys are best prepared by

A.

electroplating

B.

Arc-welding

C.

reducing and mixture of their metallic

D.

cooking a molten of the metals

Correct answer is D

Alloy is a metal that consist of two or more metals mixed together e.g. is mass which is an alloy of copper and zinc. Are not prepared with option A,B,C, and the do not result in mixture and metals together

534.

Electronic configuration of an element 13 in the subsidiary energy level is

A.

\( 1s^2 2s^2 2p^6 3s^2 3p^1 \)

B.

\( 1s^22s^2 2p^4 3p^1 3s^1 \)

C.

\( 1s^2 2s^2 2p^6 3s^2 3p^3 \)

D.

\( 1s^1 2s^2 2p^6 3s^2 3p^4 \)

Correct answer is A

No explanation has been provided for this answer.

535.

Which of the following gives a precipitation when treated with NaOH Solution?

A.

AlCl3

B.

NH4Cl

C.

Na2CO3

D.

CH3COONa

Correct answer is A

AlCl3 will give a precipitate when treated with solution. Option B,C,D will not give a precipitate when treated with NaOH solution