WAEC Chemistry Past Questions & Answers - Page 20

96.

What amount of electricity is required to deposit one mole of aluminium from a solution of AlCl3?

A.

One Faraday

B.

One ampere

C.

Three Faradays

D.

Three amperes

Correct answer is C

AlCl3 → Al3+ + 3Cl-
At cathode:
Al3+ + 3e- → Al
3 mole of electrons corresponds 3 F charge
So, required charge =3 F

97.

The following compounds are condensation polymers except

A.

nylon

B.

protein

C.

starch

D.

polyethene

Correct answer is D

Condensation polymers are any kind of polymers whose process of polymerization involves a condensation reaction.

98.

The cleansing effect of soap is low in acidic water because of

A.

the formation of unionized fatty acid.

B.

increase in the pH of the soap molecules.

C.

anti-biodegradable effect of hydrogen ions

D.

the hardness of the acidic water.

Correct answer is A

Soaps cannot be used in acidic condition because they lose their cleansing effect due to the formation of long chain fatty acids

99.

Which of the following sugars is a product of the condensation of monosaccharides?

A.

galactose

B.

maltose

C.

glucose

D.

fructose

Correct answer is B

Maltose is produced by the enzymatic hydrolysis of starch (a homopolysaccharide) catalyzed by the enzyme amylase.

100.

The by-product of fermentation of sugar is

A.

carbon(IV) oxide.

B.

ethanoic acid.

C.

propanol

D.

propan-1, 2, 3- triol.

Correct answer is A

Ethanol fermentation, also called alcoholic fermentation, is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by-products