Question

In which of the following processes entropy increases?

1. A liquid evaporates to vapour.
2. Temperature of a crystalline solid lowered from 130 K to 0 K.
3. \[\ce{2NaHCO3_{(s)} -> Na2CO3_{(s)} + CO2_{(s)} + H2O_{(g)}}\]
4. \[\ce{Cl2_{(g)} -> 2Cl_{(g)}}\]

Choose the correct answer from the options given below:

Options

• A, C and D

• C and D

• A and C

• A, B and D

Answer 1

A, C and D

Explanation:

Entropy increases with an increase in disorder, or randomness, in the system.

Randomness increases with an increase in temperature.

In system A, liquid evaporates to vapours i.e., randomness increases, and automatically, entropy increases.

In system B, temperature is lowered, i.e., randomness is lowered and entropy is also lowered.

In system C, a solid reactant is converted into gas, i.e., randomness increases and entropy also increases.

In system D, a molecule is converted into its corresponding atoms so randomness and entropy both increase.

Therefore, the A, C, and D options are correct.