Statement-1: The heat absorbed during isothermal expansion of an ideal gas against vacuum is zero.Statemept-2 : In isothermal process, change in internal energy is always zero, irrespective of ideal or real gas.a)Statement-2 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1.b)Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1.c)Statement-1 is True, Statement-2 is False.d)Statement-1 is False, Statement-2 is True.Correct answer is option 'C'. Can you explain this answer?

Question

Answer

Statement-1: The heat absorbed during isothermal expansion of an ideal gas against vacuum is zero.

Statement-2: In isothermal process, change in internal energy is always zero, irrespective of ideal or real gas.

The correct answer is option 'C', Statement-1 is True and Statement-2 is False.

Explanation:

Statement-1: The heat absorbed during isothermal expansion of an ideal gas against vacuum is zero.

When an ideal gas expands, it does work against the external pressure to overcome it. In the case of an isothermal expansion, the gas expands while maintaining a constant temperature. According to the first law of thermodynamics, the change in internal energy of a system is given by:

ΔU = Q - W

Where ΔU is the change in internal energy, Q is the heat absorbed by the system, and W is the work done on the surroundings.

In the case of an isothermal expansion, since the temperature is constant, the change in internal energy is zero. Therefore, ΔU = 0.

ΔU = Q - W
0 = Q - W
Q = W

Since the work done by the gas is positive (gas expands against vacuum), the heat absorbed by the system is also positive. Therefore, the heat absorbed during isothermal expansion of an ideal gas against vacuum is not zero. Hence, Statement-1 is False.

Statement-2: In isothermal process, change in internal energy is always zero, irrespective of ideal or real gas.

In an isothermal process, the temperature of the system remains constant. For an ideal gas, the internal energy depends only on its temperature. Therefore, in an isothermal process, the change in internal energy is zero for both ideal and real gases. So, Statement-2 is True.

Conclusion:

Statement-1 is False because the heat absorbed during isothermal expansion of an ideal gas against vacuum is not zero.

Statement-2 is True because in an isothermal process, the change in internal energy is always zero, irrespective of ideal or real gas.

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