JAMB Chemistry Past Questions & Answers - Page 346

1,727.

Two equal bulbs, one containing ammonia and the other nitrogen are opened mouth - to - mouth to each other at room temperature. The entropy in the mixture of gases is likely to?

A.

remain unchange

B.

increase

C.

decrease

D.

change

Correct answer is B

When two or more gases are mixed together at constant volume, there is an increase in entropy.

1,728.

C(s) + H2O(g) → H2(g) + CO2(g)
ΔG for the reaction above at 1300k is -43KJ. At this temperature, the reaction is?

A.

not feasible

B.

at equilibrium

C.

feasible

D.

exothermic

Correct answer is C

For a reaction to be feasible, ΔG has to be negative.

1,729.

What current will deposit 3.25g of zinc in 2hrs?
[Zn = 65, F = 96500 mol-]

A.

3.25A

B.

2.00A

C.

1.34A

D.

0.67A

Correct answer is C

No explanation has been provided for this answer.

1,730.

Which of the following metals is purified commercially by electrolysis?

A.

Zn

B.

Fe

C.

Sn

D.

Cu

Correct answer is D

Electrolysis is used extensively in metallurgical processes, such as in extraction (electrowinning) or purification (electrorefining) of metals from ores or compounds and in deposition of metals from solution (electroplating).

Copper is purified by electrolysis . Electricity is passed through solutions containing copper compounds, such as copper(II) sulfate.