As the relative molecular mass of carbon dioxide (44.0) is greater than air (about 28.0), molecules of carbon dioxide gas diffuse into the porous pots lower than air can diffuse out. This results in a decrease in pressure in the porous pot causing the water level at arm X to rise ininitially.
•The water level at A falls to the original level when the concentration of carbon dioxide and air is the same inside and outside the porous pot, i.e. there is no net diffusion of gases in both direction.
