WAEC Chemistry Past Questions & Answers - Page 169

841.

Which of the following substances is suitable solvent for perfumes?

A.

Benzene

B.

Ethanol

C.

Turpentine

D.

Water

Correct answer is B

No explanation has been provided for this answer.

842.

What product is formed at the cathode during the electrolysis of concentrated sodium chloride solution using carbon electrodes?

A.

Chlorine

B.

Hydrogen

C.

Oxygen

D.

Sodium

Correct answer is B

No explanation has been provided for this answer.

843.

What is the oxidation number of chromium in K2CrO4?

A.

+1

B.

+2

C.

+4

D.

+6

Correct answer is D

K2CrO4 (O.N of K) X 2 + O.N of Cr + (O.N of oxygen) X 4 = 0
1 X 2 + X + -2 X 4 = 0
2 + x + -8 = 0
2 + x - 8 = 0
x = 8 - 2 = + 6

844.

Which of these cell notations is the correct representation of a Daniell cell?

A.

Zn(s) / Zn2+(aq) // Cu2+(aq)/Cu(s)

B.

Cu(s) / CU2+(aq) // Zn2+(aq) / Zn(s)

C.

Zn2+(aq) / Zn(s) // Cu2+(aq) /Cu(s)

D.

Cu2+(aq) / Cu(s) // Zn(s) / Zn2+(aq)

Correct answer is A

No explanation has been provided for this answer.

845.

Consider the reaction represented by the following equation: N2(g) + 3H2(g) ⇌ 2NH3(g); ∆H = - 92kJmol1. Finely divided iron is used as catalyst in the reaction in order to

A.

lower the value of ∆H

B.

increase the time for attainment of equilibrium

C.

shorten the time for attainment of equilibrium

D.

decrease the yield of ammonia

Correct answer is C

No explanation has been provided for this answer.