What gas expands the most when heated?

Answer 1

Under equal pressures, all gases expand at the same rate, provided external pressure remains the same.

The effect of heat on the expansion of gases is stated in Charles' Law (see related link).

Answer 2

Because in gases, molecules are far apart from each other that even they can't properly kiss / touch to eacj other and one can consider gas molecules as if people shopping in the bazar and finally towards thrir homes.

Due tothis largr distance between the molecules tend to expand the most.

Two factors determine the expansion of the molecules;

1- Intermoleculars forces

2- Intermoleculars distanc

Greater the intermolecular distances, Lesser the interolecular attraction.

As in the gases intermoleculra distances is large so the intermolecular forces are small. Due to this, the gases tend to expand the most.