JEE Main levelOne or more correct optionsDifficulty 2 of 3sc033
For the physisorption of a gas on a solid surface at constant temperature, which of the following are correct?
AΔH<0
BΔS<0 because the gas loses freedom of motion
CΔG<0 for the process to occur spontaneously
DRaising the temperature makes adsorption more favourable because −TΔS becomes more negative
Answer: A, B, C
Adsorption is exothermic and ordering, so ΔH<0 and ΔS<0, and spontaneous adsorption needs ΔG<0. Since ΔS<0, the term −TΔS is positive and grows with T, making adsorption less favourable, so statement 4 is wrong.