Question

Identify the correct statements from the following:

• A. I, II only
• B. II, III only
• C. I, III only
• D. I, II, III

Hint:

To verify the correctness of thermodynamic statements, refer to the fundamental laws like the third law of thermodynamics and principles of calorimetry.

Answer 1

The Correct Option is D

Analyzing the Given Statements:

Statement I:

\( \Delta G = 0 \quad \text{for a reaction at equilibrium} \)

✅ This statement is correct. For any system in a state of dynamic equilibrium, the Gibbs free energy change (\( \Delta G \)) becomes zero. This is a key thermodynamic condition for equilibrium in both chemical and physical processes.

Statement II:
📘 This is a restatement of the Third Law of Thermodynamics, which asserts that the entropy of a perfect crystalline substance approaches zero as the temperature approaches absolute zero (0 K). Therefore, this statement is also correct.

Statement III:

\( \Delta U \quad \text{of a reaction can be determined using a bomb calorimeter} \)

✅ This is correct as well. A bomb calorimeter operates at constant volume and is used to measure the internal energy change (\( \Delta U \)) of a chemical reaction—commonly combustion—by monitoring the heat released or absorbed.

Conclusion:
All three statements are scientifically accurate and consistent with core thermodynamic principles.

Final Answer: All three statements are correct.

Answer 2

We are given three statements. Let's analyze them: 
Statement I:

\( \Delta G = 0 \quad \text{for a reaction at equilibrium.} \)

This is correct because for a reversible reaction at equilibrium, the change in Gibbs free energy is zero (\(\Delta G = 0\)).
Statement II: The entropy of pure crystalline solids approaches zero as the temperature approaches absolute zero.

This is the third law of thermodynamics, which states that the entropy of a perfect crystalline solid approaches zero at absolute zero temperature.
Statement III:

\( \Delta U \quad \text{of a reaction can be determined using bomb calorimeter.} \)

This is correct because a bomb calorimeter is designed to measure the change in internal energy (\(\Delta U\)) for a reaction at constant volume.
Thus, all three statements are correct.