JEE Main 2020 — Surface Chemistry Question with Solution

(a) When gas is adsorbed on metal surface.
$\Delta \mathrm{H}$ become less negative with progress of reaction because number of active sites decreases.
(b) Gas with greater value of critical temperature $\left({\mathrm{T}}_{\mathrm{C}}\right)$ absorbed more. As ${\mathrm{T}}_{\mathrm{C}}\left({\mathrm{NH}}_3\right)>{\mathrm{T}}_{\mathrm{C}}\left({\mathrm{N}}_2\right)$ So ${\mathrm{NH}}_3$ absorbed more than ${\mathrm{N}}_2$.

Statement (c) is wrong because residual forces decrease as adsorption proceeds further.

Statement (d) is also wrong because temperature opposes extent of adsorption.