As per Gilliland's equation, the diffusivity is

Directly proportional to $\text{'}$T$1\mathrm{.}5\text{'}$

Inversely proportional to $\text{'}$P$\text{'}$

Dependent on the molecular volume & molecular weight of components

All $\text{'}$a$\text{'},\text{'}$b$\text{'}$ & $\text{'}$c$\text{'}$