JAMB Chemistry Past Questions & Answers - Page 384

1,916.

The oxidation state of chlorine in HClO4 is

A.

-5

B.

-1

C.

+1

D.

+7

Correct answer is D

No explanation has been provided for this answer.

1,917.

What volume of 0.5 mol dm-3 H2SO4 will exactly neutralize 20cm3 of 0.1 mol dm-3 NaOH solution?

A.

2.0 cm3

B.

5.0 cm3

C.

6.8 cm3

D.

8.3 cm3

Correct answer is A

2NaOH + H2SO4 → Na2SO4 + 2H2O
CaVa/CbVb = ratio of acid/ratio of base
(0.5 * Va)/(0.1 * 20) = 1/2
∴ Va = 2.0cm

1,918.

Which of the following compound is a normal salt?

A.

NaHS

B.

NaHSO4

C.

NaHCO3

D.

Na2CO3

Correct answer is D

No explanation has been provided for this answer.

1,919.

Calcium tetraoxosulphate (VI) dissolves in water only sparingly to form a

A.

solution

B.

suspension

C.

precipitate

D.

colloid

Correct answer is C

No explanation has been provided for this answer.

1,920.

The solubility in mol dm/-3 of 20g of CuSO4 dissolved in 100g of water at 180o is
[Cu = 64, S = 32, O =16]

A.

0.13

B.

0.25

C.

1.25

D.

2.00

Correct answer is C

Relative molecular mass of CuSO4 = 64 + 32 + 16 * 4 = 160
The number of moles of CUSO4 = reacting mass/molecular mass = 20/160 = 0.125
100g of water dissolved 0.125m of CuSO4
100g of water will dissolve (0.125 * 1000)/100 = 1.25mol dm3