🔥 100 Thermodynamics MCQs with Answers (Laws, Cycles & Entropy) – Practice Test

Practice Thermodynamics MCQs with answers covering laws of thermodynamics, heat engines, entropy, and thermodynamic cycles

Attempt all 100 questions, choose the correct option, and check your live score instantly at the end

Question 1: For a reversible cyclic process operating between two thermal reservoirs, which condition must be satisfied for maximum thermal efficiency according to the second law of thermodynamics?

Question 2: In a steady-flow adiabatic turbine, neglecting kinetic and potential energy changes, the work output per unit mass is equal to:

Question 3: Which statement best describes the physical significance of entropy increase in an isolated system?

Question 4: For an ideal gas undergoing isentropic compression, which relation holds true?

Question 5: In a Rankine cycle, increasing boiler pressure while keeping condenser pressure constant will:

Question 6: In a Carnot cycle, heat rejection occurs during:

Question 7: The Clausius inequality becomes equality for:

Question 8: In a Brayton cycle, regeneration improves efficiency when:

Question 9: Availability (exergy) of a system becomes zero when:

Question 10: In an irreversible adiabatic process, entropy of the system:

Question 11: In Otto cycle, increasing compression ratio leads to:

Question 12: For a throttling process, which property remains constant?

Question 13: In a reversible process, total entropy change of universe is:

Question 14: In Rankine cycle, reheating is used to:

Question 15: For an ideal gas, internal energy depends only on:

Question 16: In Brayton cycle, maximum efficiency depends on:

Question 17: Entropy generation is zero for:

Question 18: In a steady flow process, energy equation is based on:

Question 19: The efficiency of Carnot engine depends on:

Question 20: In Diesel cycle, heat addition occurs at:

Question 21: Availability destruction is directly proportional to:

Question 22: In Rankine cycle, condenser pressure is lowered to:

Question 23: For a polytropic process PV^n = constant, when n = γ, the process is:

Question 24: In thermodynamic cycles, area under P-V curve represents:

Question 25: In a thermodynamic system undergoing a completely reversible cycle, what is the net change in entropy of the system and surroundings combined?

Question 26: In a closed system undergoing a non-flow reversible process, the maximum work output is achieved when the process is carried out under which condition?

Question 27: In a steady flow compressor, if the inlet kinetic energy is negligible and heat loss occurs to surroundings, the work input required will:

Question 28: In a thermodynamic cycle, if the area enclosed on the T-S diagram increases while the heat rejection remains constant, what can be inferred about the cycle?

Question 29: In an irreversible adiabatic process, the entropy of the system increases primarily due to:

Question 30: For an ideal gas undergoing polytropic compression, when the polytropic index is greater than the specific heat ratio, the process is:

Question 31: In Rankine cycle with regeneration, the primary purpose of feedwater heating is to:

Question 32: In a Brayton cycle operating at very high pressure ratio, the efficiency trend will:

Question 33: The concept of availability is directly related to:

Question 34: In a refrigeration cycle, coefficient of performance increases when:

Question 35: In a reversible heat engine, the efficiency becomes maximum when:

Question 36: In a gas power cycle, if intercooling is perfectly done between compressor stages, the work input will:

Question 37: In thermodynamic systems, metastable states are characterized by:

Question 38: In an open system at steady state, the mass flow rate remains constant because:

Question 39: In a Carnot refrigerator, the coefficient of performance depends on:

Question 40: In a polytropic expansion, if index is equal to one, the process is:

Question 41: In thermodynamic cycles, irreversibility leads to:

Question 42: In a vapor compression cycle, throttling process results in:

Question 43: In a reversible adiabatic process, the entropy change is:

Question 44: In a Rankine cycle, superheating of steam mainly helps to:

Question 45: In Brayton cycle, regeneration is not effective when:

Question 46: In thermodynamics, dead state refers to condition where:

Question 47: In an ideal Rankine cycle, pump work is small because:

Question 48: In a closed system, energy transfer as heat occurs due to:

Question 49: In thermodynamic analysis, exergy destruction is associated with:

Question 50: In a steady flow heat exchanger, if there is no heat loss to surroundings, the energy balance depends mainly on:

Question 51: In a closed system undergoing a cyclic process, if the net heat transfer is zero, the work done by the system will be:

Question 52: In a steady flow nozzle, if inlet velocity is very small and expansion is adiabatic, the exit velocity mainly depends on:

Question 53: In thermodynamic cycles, mean effective pressure is defined as:

Question 54: In a Rankine cycle with reheating, the primary advantage is:

Question 55: In an irreversible expansion process, the work output compared to reversible expansion between same states is:

Question 56: In a gas turbine cycle, increasing turbine inlet temperature results in:

Question 57: In thermodynamics, property that depends on path followed is called:

Question 58: In a steady flow device, stagnation enthalpy remains constant when:

Question 59: In a reversible isothermal expansion of an ideal gas, the heat transfer is equal to:

Question 60: In a Carnot engine, if sink temperature increases while source remains constant, efficiency will:

Question 61: In thermodynamic equilibrium, the system must satisfy:

Question 62: In a Brayton cycle, the compressor work is minimized when:

Question 63: In a refrigeration cycle, throttling process is irreversible because:

Question 64: In an adiabatic mixing process of two streams, the final temperature depends on:

Question 65: In thermodynamics, an intensive property is one which:

Question 66: In a Rankine cycle, the quality of steam at turbine exit affects:

Question 67: In an isentropic process, the entropy remains constant because:

Question 68: In a closed system, the first law can be written as:

Question 69: In a gas undergoing free expansion, the process is:

Question 70: In a Carnot refrigerator, the work input is minimum when:

Question 71: In thermodynamic processes, irreversibility is mainly caused by:

Question 72: In a vapor compression system, compressor work depends on:

Question 73: In a steady flow turbine, if kinetic energy at outlet increases, the work output will:

Question 74: In thermodynamics, the zeroth law establishes the concept of:

Question 75: In a closed system, work transfer occurs due to:

Question 76: In thermodynamic cycles, efficiency is maximum when:

Question 77: In a Brayton cycle with regeneration, efficiency improves because:

Question 78: In a throttling process, temperature change depends on:

Question 79: In thermodynamic systems, a quasi static process is one which:

Question 80: In a Rankine cycle, superheating increases efficiency because:

Question 81: In a gas power cycle, reheating increases work output because:

Question 82: In thermodynamics, the availability is destroyed due to:

Question 83: In a refrigeration system, COP is highest when:

Question 84: In thermodynamics, entropy can be considered as a measure of:

Question 85: In a steady flow compressor, work input increases if:

Question 86: In thermodynamic analysis, control volume refers to:

Question 87: In a gas turbine, intercooling reduces:

Question 88: In thermodynamics, the second law introduces the concept of:

Question 89: In a Carnot cycle, all processes are:

Question 90: In a steady flow heat exchanger, if heat loss is neglected, energy balance depends on:

Question 91: In thermodynamics, reversible work is always:

Question 92: In an irreversible process, entropy generation is:

Question 93: In a gas power cycle, efficiency can be improved by:

Question 94: In thermodynamic systems, isolated system means:

Question 95: In refrigeration cycles, subcooling increases:

Question 96: In a thermodynamic process, work done is maximum when:

Question 97: In thermodynamics, a heat engine converts:

Question 98: In a Carnot engine, if both source and sink temperatures double, efficiency will:

Question 99: In thermodynamic cycles, net work output is represented by:

Question 100: In thermodynamics, entropy change for an isolated system is:

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🔥 100 Thermodynamics MCQs with Answers (Laws, Cycles & Entropy) – Practice Test

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