WAEC Chemistry Past Questions & Answers - Page 107

531.

Which of the following substances would not produce ethanol when fermented?

A.

Cane sugar

B.

Glucose

C.

Starch

D.

Vinegar

Correct answer is D

Vinegar is a product from fermentation. It can be gotten from the fermentation of ethanol.

532.

Consider the following reaction equation: C\(_{16}\)H\(_{34}\) → C\(_5\)H\(_{12}\) + C\(_{11}\)H\(_{22}\). The process represented by the equation is

A.

cracking

B.

fermentation

C.

polymerization

D.

reforming

Correct answer is A

In the reaction, a complex hydrocarbon is broken down into two simpler hydrocarbons. This is cracking.

533.

The oxidation number of Fe in [Fe(CN)\(_6\)]\(^{3-}\) is

A.

+3

B.

+2

C.

-2

D.

-3

Correct answer is A

Let the oxidation number of Fe in the compound [Fe(CN)\(_6\)]\(^{3-}\) be x.

x + 6(-1) = -3

x - 6 = -3;

x = -3 + 6

x = +3

534.

Which of the following devices function on redox reaction? l. Dry cell ll. Car battery III. Electric generator

A.

l and lll only

B.

ll and lll only

C.

l and ll only

D.

l, ll and lll

Correct answer is C

No explanation has been provided for this answer.

535.

Consider the reaction represented by the following equation: CuO\(_{(s)}\) + H\(_2\)SO\(_{4(aq)}\) → CuSO\(_{4(aq)}\) + H\(_2\)O\(_{(l)}\). Which of the following factors will not affect the rate of the reaction?

A.

Particle size of CuO(s)

B.

Concentration of H2SO4(aq)

C.

Temperature of the reacting mixture

D.

Pressure of reaction system

Correct answer is D

The reaction rate between a solid and liquid will not be affected by pressure. Pressure majorly affects the reaction rate for gases.