Question

In which of the following processes entropy increases?
A. A liquid evaporates to vapour.
B. Temperature of a crystalline solid lowered from 130 K to 0 K.
C. 2NaHCO₃(s) → Na₂CO₃(s)+CO₂(g)+H₂O(g)
D. Cl₂(g) → 2Cl(g)
Choose the correct answer from the options given below:

• A. A and C
• B. A, B and D
• C. A, C and D
• D. C and D

Answer 1

The Correct Option is C

In which of the following processes entropy increases?

A. A liquid evaporates to vapour.

B. Temperature of a crystalline solid lowered from 130 K to 0 K.

C. 2NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g)

D. Cl2(g) → 2Cl(g)

Choose the correct answer from the options given below:

Explanation:

Entropy (ΔS) is a measure of disorder or randomness in a system. Entropy increases when there is an increase in disorder.

A. A liquid evaporates to vapour.

When a liquid evaporates, it changes to a gaseous state, which has higher disorder than a liquid. Therefore, entropy increases. (ΔS > 0)

B. Temperature of a crystalline solid lowered from 130 K to 0 K.

As the temperature of a crystalline solid is lowered, the particles become more ordered, reducing entropy. (ΔS < 0)

C. 2NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g)

In this reaction, a solid reactant decomposes into a solid and gaseous products. Gases have much higher disorder than solids, so entropy increases. (ΔS > 0)

D. Cl2(g) → 2Cl(g)

A diatomic molecule dissociates into two individual gaseous atoms, which increases the number of particles and disorder. Therefore, entropy increases. (ΔS > 0)

Conclusion:

The processes where entropy increases are A, C, and D