WAEC Chemistry Past Questions & Answers - Page 283

1,411.

Which of the following compounds will undergo additional reactions?

A.

Ethyne

B.

Butane

C.

Pentane

D.

Tetrachloromethane

E.

Ethanol

Correct answer is A

No explanation has been provided for this answer.

1,412.

When a solid melts and consequently boils, there is

A.

a gradual increase in the average kinetic energy of the particles

B.

a sudden decrease in the kinetic energy of the particles

C.

no change in the average kinetic energy of the particles

D.

a rapid change in the nature of bonding of the components

E.

a change in the size of the fundamental particles

Correct answer is A

- When a metal melts or boils, this is a change of physical state. Energy is transferred to a substance to melt or boil it.

- an increase in temperature will increase the average kinetic energy of the molecules.

- This energy is needed to overcome the forces of attraction between the metal ions and the delocalize electrons in the metal. The more energy needed, the higher the melting point or boiling point .

1,413.

Aluminum is above iron in the electrochemical series, yet iron corrodes easily on exposure to air while aluminium does not. This is because aluminium

A.

has a lower density than iron

B.

is a better conductor than iron

C.

does not corrode spontaneously

D.

forms thin layer of inert oxide in moist air

E.

forms amphoteric oxides while iron does not

Correct answer is D

No explanation has been provided for this answer.

1,414.

The heat accompanying the reaction represented by the equation H2O (l) → H 2O(g) is described as the heat of

A.

solution

B.

neutralization

C.

vaporization

D.

sublimation

E.

activation

Correct answer is C

No explanation has been provided for this answer.

1,415.

The electronic configuration 1s2 22s 22p 63s23p 6 is that of a

A.

noble gas

B.

Group ll element

C.

Group lll element

D.

Group V element

E.

Group VI element

Correct answer is A

No explanation has been provided for this answer.