Thermodynamics MCQ Set 5
THERMODYNAMICS MCQ SET 1
Q1. The device that increases the pressure of a gas is:
A) Turbine
B) Compressor
C) Condenser
D) Evaporator
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Answer: B) Compressor
Explanation: Compressor raises the pressure of a gas by doing work on it.
Q2. The area under a PV curve represents:
A) Heat transfer
B) Work done
C) Pressure change
D) Temperature change
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Answer: B) Work done
Explanation: In a P-V diagram, the area under the process curve gives the work done by the system.
Q3. The first law of thermodynamics for a closed system undergoing a cycle is:
A) ΔU = 0
B) Q = W
C) Q – W = 0
D) All of the above
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Answer: D) All of the above
Explanation: For a cyclic process, change in internal energy is zero, so net heat = net work.
Q4. The Kelvin temperature scale starts from:
A) Freezing point of water
B) Boiling point of water
C) Absolute zero
D) Room temperature
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Answer: C) Absolute zero
Explanation: Kelvin scale starts from 0 K, the point of zero molecular energy.
Q5. The internal energy of an isolated system:
A) Increases
B) Decreases
C) Remains constant
D) Becomes zero
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Answer: C) Remains constant
Explanation: No heat or work crosses the boundary in an isolated system.
Q6. A perfect gas follows the equation PV = constant in which process?
A) Isothermal
B) Isochoric
C) Isobaric
D) Adiabatic
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Answer: A) Isothermal
Explanation: For isothermal process, temperature is constant, hence PV = constant.
Q7. The property which indicates the degree of disorder in a system is:
A) Enthalpy
B) Entropy
C) Internal energy
D) Free energy
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Answer: B) Entropy
Explanation: Entropy measures randomness or disorder in a system.
Q8. The second law of thermodynamics tells us about:
A) Quantity of energy
B) Direction of energy flow
C) Conservation of energy
D) Heat capacity
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Answer: B) Direction of energy flow
Explanation: It states that heat flows naturally from higher to lower temperature.
Q9. During a throttling process, the temperature of gas:
A) Always increases
B) Always decreases
C) May increase or decrease
D) Remains constant
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Answer: C) May increase or decrease
Explanation: It depends on the Joule-Thomson coefficient of the gas.
Q10. The term “quasi-static process” means:
A) Very fast process
B) Reversible process
C) Very slow process near equilibrium
D) Non-equilibrium process
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Answer: C) Very slow process near equilibrium
Explanation: Quasi-static process proceeds infinitely slowly so that the system remains in equilibrium throughout.