Q1: The diffusivity, D_AB (for component A diffusing in B) is equal to the diffusivity D_BA (for component B diffusing in A) for a binary mixture of

ANS:C - ideal gases

The diffusivity 𝐷𝐴𝐵DAB​ (for component A diffusing in B) being equal to the diffusivity 𝐷𝐵𝐴DBA​ (for component B diffusing in A) for a binary mixture typically holds true for ideal gases. In ideal gas mixtures, the diffusivities of the components are primarily determined by their molecular masses and are not significantly affected by the identity of the other components in the mixture. Therefore, the diffusivity of component A in component B (𝐷𝐴𝐵DAB​) is equal to the diffusivity of component B in component A (𝐷𝐵𝐴DBA​). In contrast, for real gases and non-Newtonian liquids, the diffusivities may not be symmetric due to factors such as molecular interactions, non-ideal behavior, and viscosity effects. As a result, 𝐷𝐴𝐵DAB​ may not be equal to 𝐷𝐵𝐴DBA​ in these cases.