Question

1) how does rate of diffusion change in diffusion of gas in a liquid on heating.

Answer 1

The rate of diffusion of gas in liquid will be high at higher temperature. Because at the higher temperature kinetic energy of gas molecules will be higher so more number of gas molecules hitting the liquid surface will be higher hence the rate of diffusion will be higher.
But if we are heating the liquid then rate of diffusion will be lower as gas molecules get enough energy to leave the liquid surface hence will not tend to diffuse in liquid.