JAMB Chemistry Past Questions & Answers - Page 342

1,706.

Polyvinyl chloride is used in the production of

A.

glass

B.

alloy

C.

pipes

D.

ceramics

Correct answer is C

Polyvinyl chloride is used in the production of pipes. Polyvinyl chloride (PVC) is an odorless and solid plastic. It is most commonly white but can also be colorless or amber. It can also come in the form of white powder or pellets. PVC is made from vinyl chloride. The chemical formula for vinyl chloride is \(C_2H_3Cl\)

1,707.

The product obtained when a mixture of benzene vapour and hydrogen are passed over nickel catalyst at 180ºC is

A.

cyclohexane

B.

cyclopentane

C.

n- hexane

D.

n - pentane

Correct answer is A

When a mixture of benzene vapour and hydrogen are passed over a nickel catalyst at 180ºc cyclohexane will be produced

1,708.

Reduction of alkanones with LialH4 produces

A.

primary alkanols

B.

secondary alkanols

C.

tertiary alkanols

D.

polyhydric alkanols

Correct answer is B

Reduction of alkanones with \(LiAlH_4\) produces secondary alkanols.

1,709.

Reduction of nitroalkanes, nitrites and amides is a route for the preparation of

A.

amines

B.

alkenes

C.

polymers

D.

detergents

Correct answer is A

Reduction of nitroalkanes, nitrites and amides is a route for the preparation of amines

1,710.

A hydrocarbon X with a molar mass of 26 consists of 92.3% carbon. What is its molecular formular?

A.

C2H2

B.

C3H3

C.

C4H4

D.

C5H5

Correct answer is A

% of H2 = 100 - 92.3 = 7.7%
mole = Carbon [92.3 / 12] = 7.7

            Hydrogen [7.7 / 1] = 7.7

divide with the lowest:


Carbon - 7.1 / 7.1 = 1

Hydrogen  - 7.1 / 7.1 = 1


empirical formula = CH


(CH)n = 26
(12 + 1)n = 26
(13)n = 26
n = 26/13 = 2


molecular formula = C\(_2\)H\(_2\)