JAMB Chemistry Past Questions & Answers - Page 18

86.

Alkanes are used mainly?

A.

in the textile industry

B.

in the hydrogenation of oils

C.

as domestic and industrial fuels

D.

as fine chemicals

Correct answer is C

Alkanes are very useful as fuels.

87.

2-methylprop-1-ene is a structural isomer of?

A.

But-1-yne

B.

2-methyl But-1-ene

C.

3-methyl prop-1-yne

D.

But-2-ene

Correct answer is D

Isomers of Butene: are But-1-ene, But-2-ene, 2-Methylpropene or 2-methylprop-1-ene

88.

How many bonding pair are present in carbon(iv)oxide? 

A.

4

B.

3

C.

2

D.

1

Correct answer is A

There are 4 bond pairs in CO₂ and no lone pairs are there.

89.

In the extraction of iron, hot air is introduced into the blast furnace through?

A.

valves

B.

open-hearths

C.

arcs

D.

tuyeres

Correct answer is D

Pre-heated air at about 600ºC is blown into the furnaces from the bottom through the tuyeres.

90.

Wrought iron is obtained by heating cast iron in a furnace with?

A.

magnetite

B.

haematite

C.

carbon(ii)oxide

D.

calcium trioxosilicate(iv)

Correct answer is B

Cast iron + haematite = wrought iron