Which of the following process is associated with a decrease in entropy?

Options

A. `H_(2) (g) rarr 2 H (g)`
B. `2 NaHCO_(3) (s) rarr Na_(2) CO_(3) (s) + CO_(2) (g) + H_(2) O (g)`
C. Temperature of a crystalline solid is raised from `0 K` to `115 K`
D. A liquid crystallizer into a solid.

Answer

D

Explanation

After freezing, the molecules attain an ordered state and, therefore entropy decreases.
(1) Here, one molecules gives two atoms, i.e., the number of particles increase leading to a more disordered state.
(2) The reactant `(NaHCO_(3))` is a solid and it has low entropy. Therefore, the products represent a condition of higher entropy.
(3) At `0 K`, the costituent particles are static and the entropy is minimum. If the temperature is reaised to `115 K`, these begin to move and oscillate about their equilibrium positions in the lattice and the system becomes more disordered. Therefore, entropy increase.