CBSE Class 9 Answered

State of a substance is basically a function of interparticle forces.

eg H₂O exist as liquid at room temperature while  H₂S  is a gas. This is because intermolecular forces in water are stronger than in H₂S .

So is the case of most of ionic compounds as ionic inieraction between oppositely charged ions is strong enough to make them a solid at room temp.

On the basis of interparticle forces only  interparticle space is defined.

 Energy of particles is a function of temperature. As water also exists as steam when temp. is raised because molecules gain energy to overcome intermolecular forces.