WAEC Chemistry Past Questions & Answers - Page 177

881.

Consider the reaction represented by the equation: 2SO\(_{2(g)}\) + O\(_{2(g)}\) ⇌ 2SO\(_{3(g)}\); ∆H = - 197 kJmol\(^{-1}\). Which of the following conditions will not increase the yield of sulphur (VI) oxide?

A.

Increase in temperature

B.

Decrease in temperature

C.

Increase in pressure

D.

Addition of O2 into the mixture

Correct answer is A

The reaction is an exothermic reaction (∆H=-197kjmol).
For continual yield of sulphur(IV)oxide, heat must be liberated.
So,increasing the temperature of the reaction will lead to reduction in yield of \(SO_3\) since it favours backward reaction which is endothermic.

882.

Which of the following compounds absorbs moisture from the atmosphere and dissolves in it?

A.

FeCI3

B.

MgSO4.7H2O

C.

Na2SO 4

D.

KCI

Correct answer is A

No explanation has been provided for this answer.

883.

When aqueous ammonia is added to one of the following solutions,a white precipitate which dissolved in excess ammonia is formed Identify the solution.

A.

ZnCl2(aq)

B.

Pb(NO3)2(aq)

C.

CuSO4(aq)

D.

FeSO4(aq)

Correct answer is A

No explanation has been provided for this answer.

884.

The indicator used in neutralizing CH3COOH and NaOH solution has pH range of

A.

3-5

B.

7-8

C.

8-103

D.

10-12

Correct answer is C

No explanation has been provided for this answer.

885.

Which of the following aqueous methods cannot be used to distinguish between a strong acid and a a weak acid?

A.

Conductivity measurement

B.

Measurement of pH

C.

Measurement of heat of neutralization

D.

Action on starch iodide paper

Correct answer is D

No explanation has been provided for this answer.