JAMB Chemistry Past Questions & Answers - Page 177

881.

The same current is passed for the same time through solutions of AgNO3 and CuSO4 connected in series. How much silver will be deposited if 1.0 g of copper is produced?
[Cu = 63.5, S = 32, O = 16, Ag = 108, N = 14]

A.

1.7g

B.

3.4g

C.

6.8g

D.

13. 6 g

Correct answer is B

From Faraday;s second law of electrolysis

\(\frac{\text{Mass of silver deposited}}{\text{Mass of copper deposited}}\) = \(\frac{\text{Equivalent mass of silver}}{\text{Equivalent mass of copper}}\)

\(\frac{\text{Mass of silver deposited}}{1.0g}\) = \(\frac{108}{63.5}\)

= 31.75g

Copper is devalent = Cu2+

Mass of silver deposited = \(\frac{108g}{31.75g}\)

= 3.30g

882.

An acid and its conjugate base

A.

can neutralise each other to form a salt

B.

differ only by a proton

C.

differ only by the opposite charges they carry

D.

are always neutral substances

Correct answer is B

No explanation has been provided for this answer.

883.

The substance ZnO dissolves in sodium hydroxide solution and mineral acid solution to give soluble products in each case. ZnO is therefore referred to as

A.

an allotropic oxide

B.

an amphoteric oxide

C.

a peroxide

D.

a dioxide

Correct answer is B

No explanation has been provided for this answer.

884.

A solution of calcium bromide contains 20 g dm 3 What is the molarity of the solution with respect to calcium bromide and bromide ions? [Ca = 40, Br = 80]

A.

0. 1, 0 . 1

B.

0. 1, 0. 2

C.

0. 1, 0. 05

D.

0.05, 0.1

Correct answer is B

No explanation has been provided for this answer.