Thermodynamics

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Q1. What is the change in internal energy of an ideal gas when it expands isothermally? (2021)

Solution:

In an isothermal process for an ideal gas, the internal energy remains constant, hence the change in internal energy is zero.

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Q2. What is the specific heat capacity of water at constant pressure (C_p)? (2020)

Solution:

The specific heat capacity of water at constant pressure is approximately 4.18 J/g°C.

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Q3. In a Carnot engine, the efficiency depends on which of the following? (2023)

Solution:

The efficiency of a Carnot engine is determined by the temperatures of the hot and cold reservoirs, given by the formula η = 1 - (T_c/T_h).

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Q4. What is the change in internal energy of an ideal gas when it is heated at constant volume? (2021) 2021

Solution:

At constant volume, the change in internal energy (ΔU) is equal to the heat added (Q). Therefore, ΔU = Q.

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Q5. In a heat engine, if the input heat is 500 J and the work done is 300 J, what is the efficiency? (2023) 2023

Solution:

Efficiency (η) = Work done / Input heat = 300 J / 500 J = 0.6 or 60%.

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Q6. What is the specific heat capacity of water? (2021) 2021

Solution:

The specific heat capacity of water is approximately 4.18 J/g°C.

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Q7. In an adiabatic process, which of the following is true? (2020)

Solution:

In an adiabatic process, there is no heat exchange with the surroundings, meaning no heat is absorbed or released.

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Q8. In an adiabatic process, which of the following remains constant? (2020)

Solution:

In an adiabatic process, there is no heat exchange, so the internal energy remains constant for an ideal gas.

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Q9. What is the efficiency of a Carnot engine operating between temperatures T1 and T2? (2019) 2019

Solution:

The efficiency (η) of a Carnot engine is given by η = 1 - (T2 / T1), where T1 is the higher temperature and T2 is the lower temperature.

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Q10. What is the change in internal energy (ΔU) for an ideal gas that expands isothermally? (2022)

Solution:

For an isothermal process, the change in internal energy ΔU = 0 for an ideal gas.