GATE MT topic:laws-thermodynamics PYQs & Answers — Page 3

Questions 21–30 of 69. Imported answers require independent review unless marked reviewed.

If for element A, the formation enthalpy and formation entropy per vacancy created are 0.5 eV and

, respectively, then the equilibrium vacancy concentration (in mole fraction) at 500 K is ________

. (Round off to two decimal places)

Given: Boltzmann constant,

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An ideal solution is formed by mixing 10

of A and 50

of B at 673

. The molar free energy of mixing ______

. (Round off to one decimal place)

Given: Universal gas constant

Atomic weight of A = 40

Atomic weight of B = 60

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At one atmosphere pressure, α-Fe transforms to γ-Fe above 912 °C. Density of γ-Fe is more than that of α-Fe. Choose the correct statement.

Your answerChoose one option.

Increasing the pressure above one atmosphere lower the α-Fe to γ-Fe transformation temperature.

Increasing the pressure above one atmosphere raises the α-Fe to γ-Fe transformation temperature.

Molar volume of γ-Fe is higher than the molar volume of α-Fe.

Pressure change will not have any effect on the α-Fe to γ-Fe transformation temperature.

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Formation of an ideal solution leads to

Your answerChoose one option.

increase in entropy

decrease in volume

increase in enthalpy

decrease in entropy

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At one atmosphere pressure, iron (Fe) and nickel (Ni) oxidize as

Identify the correct statement.

Given: Temperature,

is in Kelvin

Your answerChoose one option.

Fe can reduce NiO at all temperatures

Fe can reduce NiO only above 1000 K

Ni can reduce FeO at all temperatures

Ni can reduce FeO only above 1000 K

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Maximum number of phases that can be in equilibrium for a 5-component system at constant temperature and pressure is __________ (in integer).

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Taking S as entropy, T as temperature, P as pressure, and V as volume, match Column I with Column II.

Column I (A) Gibbs Free Energy (B) Helmholtz Free Energy (C) Enthalpy (D) Internal Energy

Column II (1) depends on T, V and composition (2) depends on T, P and composition (3) depends on S, P and composition (4) depends on S, V and composition

Your answerChoose one option.

A – 2, B – 1, C – 3, D – 4

A – 4, B – 3, C – 2, D – 1

A – 3, B – 1, C – 4, D – 2

A – 2, B – 1, C – 4, D – 3

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Concerning the chemical potentials of components in a binary system at constant pressure, the correct statement(s) is/are

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

For single-phase equilibrium at a given temperature, chemical potentials of the components change with alloy composition.

For two-phase equilibrium at a given temperature, chemical potential of any component in both phases is the same.

For two-phase equilibrium at a given temperature, chemical potentials of the components change with alloy composition.

For single-phase equilibrium at a given composition, chemical potentials of the components do not change with temperature.

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Enthalpy of formation of an A–B regular solution containing 80 atomic percent A is 3.36

. The activity coefficient of A at 500 K for the solution containing 40 atomic percent A is __________ (round off to 1 decimal place).

Given: Universal gas constant, R = 8.314

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According to Sieverts’ law, the equilibrium solubility of N₂ (gas) in molten steel is proportional to __________

Given: Equilibrium partial pressure of N₂ (gas) is

Your answerChoose one option.

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GATE MT topic:laws-thermodynamics PYQs

Question 53

Question 56

Question 11

Question 12

Question 14

Question 32

Question 36

Question 47

Question 55

Question 12