GATE XE Second Law of Thermodynamics PYQs & Answers — Page 2

Questions 11–20 of 43. Imported answers require independent review unless marked reviewed.

A closed system containing an unknown substance undergoes an adiabatic process governed by the relation

, where

is pressure,

is volume, and

is the ratio of specific heats. For this scenario, which of the following statements is/are always TRUE?

Your answerSelect all correct options. You can choose more than one.

The substance is an ideal gas and process is reversible

The substance is a liquid and process is reversible

The substance is a non-ideal gas and process is reversible

The substance is an ideal gas and process is NOT reversible

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Two rigid, impermeable containers

and

are filled with an ideal gas. They are allowed to exchange heat only with each other and not with the surroundings.

, and

represent the pressure, total volume, number of moles, and temperature, respectively. At equilibrium, which of the following conditions is/are necessarily satisfied?

(Subscripts

and

represent properties of the gas in the respective containers.)

Your answerSelect all correct options. You can choose more than one.

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10 kg of water at 300 K is poured into a bucket containing 10 kg of water at 350 K. Heat capacity of water is 4.2 kJ/kg.K. Neglecting any heat losses to the surroundings, the change in the entropy (in kJ/K) of the system during this process (rounded off to two decimal places) is

Your answerChoose one option.

0.00

0.25

0.50

0.75

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A Carnot engine operates between two temperatures T₁ and T₂ such that T₁ > T₂. If the thermal efficiency of the engine is to be increased by changing one of the temperatures by a constant amount ΔT > 0, which one of the following cases will give the highest increase in efficiency?

Your answerChoose one option.

Increasing T₁ by ΔT while keeping T₂ constant

Decreasing T₁ by ΔT while keeping T₂ constant

Increasing T₂ by ΔT while keeping T₁ constant

Decreasing T₂ by ΔT while keeping T₁ constant

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Two moles of a monoatomic ideal gas at 10 atm and 300 K is expanded isothermally and reversibly to a pressure of 2 atm. The absolute value of work done by the system is (in kJ) __________ (rounded off to two decimal places)

Given: R = 8.31 J mol⁻¹ K⁻¹, 1 atm = 101 kPa

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The following statements are given: (i) The third law of thermodynamics deals with the entropy of a substance at the absolute zero temperature. (ii) Entropy of any non-crystalline structure is zero at absolute zero temperature. (iii) At the absolute zero temperature, the crystal structure has maximum degree of order. (iv) The thermal energy of the substance at absolute zero temperature is maximum. The correct option describing these statements is

Your answerChoose one option.

Only (i) is correct

Only (ii) is correct

Both (i) and (iii) are correct

Both (i) and (iv) are correct

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A 5 kg metal block (

kJ/kg-K) at 373 K is submerged into 10 kg of water (

kJ/kg-K) at 293 K in an insulated rigid container without spilling. Assuming thermal equilibrium is reached, the approximate entropy change of the universe is

Your answerChoose one option.

−0.565 kJ/K

0.073 kJ/K

0.642 kJ/K

0.963 kJ/K

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An office uses a heat pump to receive 500 kJ/day heat in winter to maintain its temperature at 300 K. The ambient temperature is 280 K. If the COP of the heat pump is 60% of its theoretical maximum value, the ratio of actual work input to the minimum theoretical work input to the heat pump is ______ (rounded off to one decimal place).

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The temperature of the working fluid in a real heat engine cycle changes during heat addition and heat rejection processes. The maximum and minimum temperatures of the cycle are

and

, respectively. If

is the thermal efficiency of a Carnot engine operating between these temperature limits, then the thermal efficiency,

of the real heat engine satisfies the relation

Your answerChoose one option.

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A Carnot heat pump extracts heat from the environment at 250 K, and supplies 6 kW of heat to a room which is maintained at a constant temperature

. The heat pump requires a power input of 1 kW for its operation. Then, the temperature of the room

is ______ K (round off to nearest integer).

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GATE XE Second Law of Thermodynamics PYQs

Question 93

Question 94

Question 100

Question 101

Question 63

Question 92

Question 99

Question 108

Question 91

Question 96