Exams › JEE Advanced › Chemistry
Correct answer: Solid catalysts catalyze gaseous reactions by chemisorption of reactant molecules onto the solid surface.
Statement A: Chemisorption requires activation energy, so it INCREASES initially with temperature (unlike physisorption which decreases). At very high temperature it may decrease. So saying it 'decreases with increasing temperature' is INCORRECT in general — it is not uniformly true. Statement B: Solid catalysts work via chemisorption of reactant molecules (active sites form chemical bonds with reactants) — CORRECT. Statement C: Adsorption converts gaseous molecules to surface-bound state (lower degrees of freedom), so entropy decreases — CORRECT (delta_S < 0; this is why adsorption is exothermic, since delta_G must be negative, delta_H must be sufficiently negative to offset -T*delta_S). Statement D: Freundlich and Langmuir isotherms both predict more adsorption with higher pressure — CORRECT. So B, C, D are correct; A is incorrect.