Q.1 Which of the following is a state function in thermodynamics?
Work
Heat
Internal Energy
Path
Explanation - Internal energy depends only on the state of the system, not on the path taken, hence it is a state function.
Correct answer is: Internal Energy
Q.2 The First Law of Thermodynamics is essentially a statement of:
Conservation of Momentum
Conservation of Energy
Conservation of Mass
Conservation of Entropy
Explanation - The First Law states that energy can neither be created nor destroyed; it only transforms from one form to another.
Correct answer is: Conservation of Energy
Q.3 Which process occurs at constant pressure?
Isochoric
Isothermal
Isobaric
Adiabatic
Explanation - An isobaric process occurs when pressure remains constant while other variables may change.
Correct answer is: Isobaric
Q.4 In an adiabatic process, there is:
No heat exchange
No change in pressure
No change in temperature
No work done
Explanation - Adiabatic means no heat is transferred to or from the system.
Correct answer is: No heat exchange
Q.5 The SI unit of entropy is:
J/mol
J/mol·K
J·K
J
Explanation - Entropy is measured in joules per mole per kelvin, representing energy dispersal per unit temperature.
Correct answer is: J/mol·K
Q.6 The efficiency of a Carnot engine depends only on:
Work done
Temperatures of reservoirs
Type of gas used
Pressure of the gas
Explanation - Carnot efficiency depends only on the temperatures of the hot and cold reservoirs, not on the working substance.
Correct answer is: Temperatures of reservoirs
Q.7 Which law states that absolute zero cannot be reached in a finite number of steps?
First Law
Second Law
Third Law
Zeroth Law
Explanation - The Third Law of Thermodynamics states that as temperature approaches absolute zero, entropy approaches a constant value and absolute zero is unattainable.
Correct answer is: Third Law
Q.8 The Zeroth Law of Thermodynamics establishes the concept of:
Internal energy
Entropy
Temperature
Work
Explanation - Zeroth Law defines temperature through thermal equilibrium, allowing us to compare temperatures between systems.
Correct answer is: Temperature
Q.9 In an isothermal process for an ideal gas:
Temperature changes
Internal energy changes
Heat supplied equals work done
No work is done
Explanation - Since internal energy remains constant in isothermal processes, heat supplied is entirely converted into work.
Correct answer is: Heat supplied equals work done
Q.10 Which quantity is extensive in nature?
Temperature
Pressure
Entropy
Density
Explanation - Extensive properties depend on the amount of matter. Entropy increases with the size of the system.
Correct answer is: Entropy
Q.11 In thermodynamics, the surroundings plus the system together are called:
Boundary
Universe
Environment
Reservoir
Explanation - The system and its surroundings together constitute the thermodynamic universe.
Correct answer is: Universe
Q.12 What is the work done in a cyclic process?
Zero
Equal to heat supplied
Equal to change in entropy
Area enclosed on P-V diagram
Explanation - In a cyclic process, the work done is represented by the area enclosed on the pressure-volume (P-V) diagram.
Correct answer is: Area enclosed on P-V diagram
Q.13 What is the Kelvin equivalent of 0 °C?
100 K
0 K
273 K
373 K
Explanation - Kelvin scale is obtained by adding 273 to the Celsius temperature. Hence, 0 °C = 273 K.
Correct answer is: 273 K
Q.14 The specific heat capacity at constant pressure is always:
Less than Cv
Equal to Cv
Greater than Cv
Zero
Explanation - Since extra heat is required to do work at constant pressure, Cp is greater than Cv.
Correct answer is: Greater than Cv
Q.15 Entropy is a measure of:
Energy
Disorder
Temperature
Work
Explanation - Entropy quantifies the degree of randomness or disorder in a system.
Correct answer is: Disorder
Q.16 Which process has no change in volume?
Isobaric
Isochoric
Isothermal
Adiabatic
Explanation - Isochoric process occurs at constant volume, so no work is done.
Correct answer is: Isochoric
Q.17 The unit of the universal gas constant R is:
J·mol⁻¹·K⁻¹
Pa·m³
K⁻¹
J/kg
Explanation - The gas constant R has the units joule per mole per kelvin.
Correct answer is: J·mol⁻¹·K⁻¹
Q.18 For an isolated system, the entropy:
Decreases
Remains constant
Increases or remains constant
Always increases
Explanation - According to the second law, entropy of an isolated system never decreases.
Correct answer is: Increases or remains constant
Q.19 The slope of an isothermal curve on a P-V diagram is:
Positive
Negative
Zero
Infinite
Explanation - Boyle’s law (PV = constant) gives a hyperbolic curve with negative slope in a P-V diagram.
Correct answer is: Negative
Q.20 At absolute zero temperature, the volume of an ideal gas is:
Infinite
Zero
Constant
Negative
Explanation - According to Charles’s law, volume of an ideal gas becomes zero at absolute zero temperature.
Correct answer is: Zero
Q.21 Heat engine efficiency can never reach 100% because:
Friction always exists
Entropy cannot decrease
Some heat must be rejected to sink
Work is always less than heat supplied
Explanation - According to the second law, no heat engine can be perfectly efficient as some heat must be rejected.
Correct answer is: Some heat must be rejected to sink
Q.22 What does Cp – Cv equal for an ideal gas?
0
R
γ
1
Explanation - For an ideal gas, the relation Cp – Cv = R holds true.
Correct answer is: R
Q.23 The ratio Cp/Cv is known as:
Gas constant
Compressibility factor
Adiabatic index
Entropy
Explanation - The ratio of specific heats Cp and Cv is called adiabatic index or γ.
Correct answer is: Adiabatic index
Q.24 A refrigerator works on the principle of:
Heat engine
Carnot theorem
Reverse Carnot cycle
Second Law of Newton
Explanation - A refrigerator is essentially a heat engine working in reverse, moving heat from cold to hot body.
Correct answer is: Reverse Carnot cycle
Q.25 In a PV diagram, the area under the curve represents:
Heat supplied
Entropy
Work done
Internal energy
Explanation - The area under the PV curve is equal to the work done by the gas in expansion or compression.
Correct answer is: Work done