Q1. The entropy of a perfect crystalline substance at absolute zero is given by: (2021)
Solution:
According to the third law of thermodynamics, the entropy of a perfect crystalline substance at absolute zero is exactly zero.
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Q2. The heat capacity at constant volume (Cv) for an ideal gas is related to which of the following? (2023)
Solution:
The heat capacity at constant volume (Cv) is directly related to the change in internal energy of the system.
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Q3. In which of the following conditions does the entropy of a system increase? (2022)
Solution:
The entropy of a system increases when a solid melts into a liquid, as the disorder of the system increases.
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Q4. The heat capacity of a substance is defined as: (2023)
Solution:
The heat capacity of a substance is defined as the amount of heat required to raise the temperature of one mole of the substance by one degree Celsius.
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Q5. In thermodynamics, the term 'system' refers to: (2022)
Solution:
In thermodynamics, the 'system' refers to the part of the universe that is being studied, while the surroundings are everything else.
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Q6. In which of the following processes is the enthalpy change (ΔH) equal to the heat absorbed at constant pressure? (2019)
Solution:
In an isobaric process, the enthalpy change (ΔH) is equal to the heat absorbed or released at constant pressure.
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Q7. The heat capacity at constant volume (Cv) is defined as: (2022)
Solution:
The heat capacity at constant volume (Cv) is defined as the amount of heat required to raise the temperature of a substance by 1°C at constant volume.
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Q8. Which of the following processes increases the entropy of the system? (2022)
Solution:
The melting of ice increases the entropy of the system as it transitions from a solid to a liquid state, which has more disorder.
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Q9. What is the change in internal energy (ΔU) for an ideal gas during an isothermal process? (2021)
Solution:
In an isothermal process for an ideal gas, the temperature remains constant, which means the internal energy does not change. Therefore, ΔU = 0.
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Q10. In thermodynamics, the term 'enthalpy' is defined as: (2022)
Solution:
Enthalpy is defined as the heat content of a system at constant pressure, represented as H = U + PV.
