MHT CET202615 April 2026Morning ShiftChemistryThermodynamics (C)Actual
Which of the following processes has S negative?
Options
- ADissolving Sugar in Water
- BAdsorption of a Gas on a Solid Surface
- C2 NH ₃(g) N ₂(g) + 3 H ₂(g)
- DSublimation of Dry Ice
Correct answer
B. Adsorption of a Gas on a Solid Surface
Step-by-step solution
Entropy ( S ) is a measure of randomness or disorder in a system. For dissolving sugar in water, solid sugar molecules break apart and mix with water, increasing the randomness. Thus, S > 0 . For the adsorption of a gas on a solid surface, the gas molecules are restricted to the surface of the solid, which decreases their translational degrees of freedom. The randomness of the system decreases, leading to S For the reaction 2 NH ₃(g) N ₂(g) + 3 H ₂(g) , the number of gaseous moles increases from 2 to 4 ( n_g = 2 ).