WAEC Chemistry Past Questions & Answers - Page 114

566.

An alkanol can be prepared by the reaction of an alkene with

A.

concentrated tetraoxosulphate (VI) acid

B.

bromine tetrachloroethane

C.

aqueous potassium tetraoxomanganate (VII)

D.

sodium hydroxide solution

Correct answer is A

An alkene reacts with conc. H\(_2\)SO\(_4\) to yield an alkyl hydrogen tetraoxosulphate (VI). The compound formed undergoes hydrolysis when boiled with water to yield an alcohol.

567.

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.

568.

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.

569.

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

570.

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.