Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

1,296.

The postulate that molecules are in constant random motion best explains why liquids

A.

can undergo solidification

B.

maintain their volumes

C.

are incompressible

D.

have no characteristic shape

Correct answer is A

No explanation has been provided for this answer.

1,297.

At ordinary temperature H\(_2\)O is a liquid while H\(_2\)S is a gas. This is because H\(_2\)O has

A.

weak intermolecular forces holding its molecules together

B.

strong hydrogen bonds holding its molecules together

C.

induced dipole-induced dipole forces between its molecules

D.

ionic force between its molecules

Correct answer is B

H\(_2\)O has stronger intermolecular dipole--dipole interaction because of the greater polarity (or a hydrogen bond). Because of the stronger intermolecular interaction H\(_2\)O is more stable and exists as a liquid.

1,298.

When a substance changes directly from the solid state to the gaseous state without forming a liquid, the substance is said to

A.

condense

B.

evaporate

C.

sublime

D.

precipitate

Correct answer is C

No explanation has been provided for this answer.

1,299.

The volume occupied by 0.4 g of hydrogen gas at s.t.p. is [H = 1. 00; Molar volume at s.t.p. = 22.4 dm3]

A.

2.24 dm3

B.

4.48dm3

C.

22.4dm3

D.

44.8dm 3

Correct answer is B

2g of H\(_2\) = 22.4 dm\(^3\)

0.4g of H\(_2\) = x,

x = \(\frac{0.4 \times 22.4}{2}\) = 4.48dm\(^3\)

1,300.

Which of the following metals would readily displace hydrogen from steam?

A.

Copper

B.

Lead

C.

Magnesium

D.

Silver

Correct answer is C

In the electrochemical series, H\(^+\) is above all the other elements in the series except Magnesium. Hence, only Mg\(^{2+}\) can displace hydrogen from a reaction.