The diffusion rate of a gas depends on several factors such as molecular weight, temperature, pressure, and the presence of other gases. In general, lighter gases will diffuse faster than heavier gases.
The molecular weight of sodium sulfite (Na2SO3) is 126.05 g/mol, while the molecular weight of sodium hydroxide (NaOH) is 40.00 g/mol. Therefore, sodium hydroxide is a lighter gas than sodium sulfite, and it will diffuse faster. Hope this helps!