Here's why:

* Molecular weight: CO2 has a molecular weight of 44 g/mol, while SO2 has a molecular weight of 64 g/mol. Lighter molecules generally diffuse faster.

* Graham's Law of Diffusion: This law states that the rate of diffusion of a gas is inversely proportional to the square root of its molecular weight.

* This means that the lighter the molecule, the faster it will diffuse.

Therefore, CO2, with its lower molecular weight, will diffuse faster than SO2.