WAEC Chemistry Past Questions & Answers - Page 244

1,216.

The alkali metals exhibit similar chemical properties because

A.

they occur in the combined state

B.

they have the same number of vallence electrons

C.

they form crystalline salts

D.

their salts are soluble in water

E.

they are highly reactive

Correct answer is B

No explanation has been provided for this answer.

1,217.

When an atom gains an electron, it becomes properties

A.

chemically inactive

B.

negatively charged

C.

oxidized

D.

a cation

E.

a complex ion

Correct answer is B

No explanation has been provided for this answer.

1,218.

The existance of two or more forms of the same element in the same physical state is known as

A.

allotropy

B.

resonance

C.

hybridization

D.

isotopy

E.

isomerism

Correct answer is A

Allotropy or allotropism is the property of some chemical elements to exist in two or more different forms, in the same physical state.

1,219.

A sample of air that has been passed through caustic potash will

A.

contain more oxygen than nitrogen

B.

rekindle a glowing splint

C.

have no action on lime water

D.

contain no water vapour

E.

be free of noble gases

Correct answer is C

- Potassium hydroxide also absorbs carbon dioxide from the air. - If carbon dioxide is bubbled through limewater, the limewater turns milky or cloudy white.

1,220.

Chlorine is prepared on a large scale by the

A.

electrolysis of concentrated sodium chloride solution

B.

action of manganese (IV) oxide on hot concentrated hydrochloric acid

C.

action of concentrated tetraoxosulphate (IV) acid on sodium chloride

D.

oxidation of concentrated hydrochloric acid with potassium tetraxosulphate (VII)

E.

action of dilute mineral acids on bleaching powder

Correct answer is A

No explanation has been provided for this answer.