WAEC Chemistry Past Questions & Answers - Page 232

1,156.

Which of the following is used widely in the manufacture of flavours and perfumes?

A.

Alkanoates

B.

Alkanones

C.

Alkanes

D.

Complex sugars

E.

Aliphatic compounds

Correct answer is A

No explanation has been provided for this answer.

1,157.

Alkanes react with the halogens mainly by

A.

oxidation

B.

polymerization

C.

addition

D.

reduction

E.

substitution

Correct answer is E

No explanation has been provided for this answer.

1,158.

The by-product of the fermentation of sugar to ethanol is

A.

propane -1,2,3-triol

B.

ethyl ethanoate

C.

ethanedioc acid

D.

propanol

E.

carbon (lV) oxide

Correct answer is E

No explanation has been provided for this answer.

1,159.

Which of the following is the relative molecular mass of a compound which has empirical formula CH\(_2\)O? (H = 1; C = 12; O = 16)

A.

42

B.

45

C.

126

D.

180

E.

145

Correct answer is D

Empirical formula = CH\(_2\)O

= 12 + (2 x 1) + 16

= 30

Molecular formula = (CH\(_2\)O)\(_n\), where n is a whole number.

= 30n

\(\therefore\) From the options, only 180 is a multiple of 30. Hence, that is the only likely molecular mass with respect to CH\(_2\)O.

1,160.

The reaction between alkanoic acids and alkanols in the presence of a mineral acid is known as

A.

saponification

B.

hydrolysis

C.

polymerization

D.

esterification

E.

dehydration

Correct answer is D

No explanation has been provided for this answer.