Question

Give two reasons to justify [5 MARKS]

(a) Water at room temperature is a liquid.
(b) An iron almirah is a solid at room temperature.

Answer 1

Reasoning out: 2.5 marks each.
Water remains a liquid at room temperature because of the following reasons:

1. Intermolecular forces between the water molecules are less.
2. Intermolecular spaces and kinetic energy among the water molecules are more.

This enables the water molecules to interchange their spaces and hence water remains in a liquid state even at room temperature.

An iron almirah remains a solid at room temperature because of the following reasons:

1. Intermolecular forces among the iron molecules are very large.
2. Intermolecular spaces as well as kinetic energy among the iron molecules are very small.

Thus, the molecules are held very very tightly, with the result, that the iron almirah has a definite shape and a definite volume, and hence a solid.