GATE CH concept:entropy PYQs & Answers

Questions 1–9 of 9. Imported answers require independent review unless marked reviewed.

Ideal nonreacting gases

and

are contained inside a perfectly insulated chamber, separated by a thin partition, as shown in the figure. The partition is removed, and the two gases mix till final equilibrium is reached. The change in total entropy for the process is ____ J/K (rounded off to 1 decimal place).

Given: Universal gas constant

J/(mol K)

atm

Diagram for Chemical Engineering question 33

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John and Jane independently performed a thermodynamic experiment, in which X and Y represent the initial and final thermodynamic states of the system, respectively. John performed the experiment under reversible conditions, for which the change in entropy of the system was

. Jane performed the experiment under irreversible conditions, for which the change in entropy of the system was

. Which one of the following relationships is CORRECT?

Your answerChoose one option.

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Consider a system where a Carnot engine is operating between a source and a sink. Which of the following statements about this system is/are NOT correct?

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

This engine is reversible.

The engine efficiency is independent of the source and sink temperatures.

This engine has the highest efficiency among all engines that operate between the same source and sink.

The total entropy of this system increases at the completion of each cycle of the engine.

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For a single component system at vapor-liquid equilibrium, the extensive variables

and

denote the Helmholtz free energy, volume, entropy, and number of moles, respectively, in a given phase. If superscripts

and

denote the vapor and liquid phase, respectively, the relation that is NOT CORRECT is

Your answerChoose one option.

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5 moles of liquid benzene, 8 moles of liquid toluene and 7 moles of liquid xylene are mixed at 25 °C and 1 bar. Assuming the formation of an ideal solution and using the universal gas constant

J mol

, the total entropy change is ________ J K

(rounded off to one decimal place).

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A substance at 4 °C has a thermal expansion coefficient

, an isothermal compressibility,

and a molar volume

mol

. If

is the molar entropy, then at 4 °C, the quantity

evaluated for the substance is __________ J mol

(rounded off to the nearest integer).

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The molar heat capacity at constant pressure

(in J mol⁻¹ K⁻¹) for n-pentane as a function of temperature (T in K) is given by

At 100 K, the rate of change of molar entropy of n-pentane with respect to temperature at constant pressure is __________ J mol⁻¹ K⁻² (round off to 2 decimal places).

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Consider a rigid, perfectly insulated, container partitioned into two unequal parts by a thin membrane (see figure). One part contains one mole of an ideal gas at pressure

and temperature

while the other part is evacuated. The membrane ruptures, the gas fills the entire volume and the equilibrium pressure is

. If

(molar specific heat capacity at constant pressure),

(molar specific heat capacity at constant volume) and

(universal gas constant) have the same units as molar entropy, the change in molar entropy

Diagram for Chemical Engineering question 3

Your answerChoose one option.

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For a single component system, vapor (subscript

) and liquid (subscript

) coexist in mechanical, thermal and phase equilibrium when

Your answerChoose one option.

(equality of specific internal energy)

(equality of specific enthalpy)

(equality of specific entropy)

(equality of specific Gibbs free energy)

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GATE CH concept:entropy PYQs

How to practice concept:entropy

Question 33

Question 19

Question 28

Question 15

Question 29

Question 47

Question 23

Question 3

Question 4