Question

Why is hot air lighter than cool air

Answer 1

Because hot air is easily remove in surrounding but the cool air push it so that the hot air is lighter than cool air
I hope it’s help you

Answer 2

1. As we know that air expands when we heat it because when air absorbs heat it's intermolecular strength decreases.

2. the reduction in intermolecular force results in increase in volume and decrease in density.

3. Due to which the hot air with low density becomes lighter and cold air remains dens as compared to hot air.

hence, hot air is lighter than the cool air.

hope it helps...