JAMB Chemistry Past Questions & Answers - Page 404

2,016.

CU2S(s) + O2(g) → 2CU(s) + SO2(g)
What is the change in the oxidation number of copper in the reaction above?

A.

+1 to 0

B.

0 to +2

C.

+2 to +1

D.

0 to +1

Correct answer is A

No explanation has been provided for this answer.

2,017.

When dissolved in water, NaOH flakes show

A.

An endothermic change

B.

An exothermic change

C.

A slow reaction

D.

A rapid reaction

Correct answer is B

No explanation has been provided for this answer.

2,018.

The Arrhenius equation expresses the relationship between the speed of a reaction and its

A.

Molecular collision

B.

Heat of reaction

C.

Catalyst

D.

Activation energy

Correct answer is D

No explanation has been provided for this answer.

2,019.

When H2S is passed into a solution of iron (III) chloride, the solution turns

A.

Pale green

B.

Pale red

C.

Brown

D.

Colourless

Correct answer is A

A reaction between Iron (iii) chloride and Hydrogen sulphide leads to the reaction

2FeCl3(aq) + H2S(g) → 2FeCl2(aq) + 2HCl(aq) + S(s)

The colour change is from REDDISH BROWN to PALE GREEN.

2,020.

PCl5(g) ↔ PCl3(g) + Cl2(g)
In the reaction above, a decrease in pressure will

A.

Decelerate the reaction

B.

Increase the yield of PCl3

C.

Increase the yield of PCl5

D.

Accelerate the reaction

Correct answer is B

No explanation has been provided for this answer.