GATE XE purpose:exam-prep PYQs & Answers — Page 48

Questions 471–480 of 1772. Imported answers require independent review unless marked reviewed.

Match each quantity in Column M with the appropriate relation from Column N. Here,

is Helmholtz function,

is pressure,

is specific volume,

is temperature,

is specific enthalpy, and

is specific entropy.

Column M: (M1)

; (M2)

; (M3)

; (M4)

Column N: (N1)

; (N2)

; (N3)

; (N4)

; (N5)

; (N6)

; (N7)

; (N8)

Your answerChoose one option.

M1-N5, M2-N1, M3-N4, M4-N7

M1-N6, M2-N2, M3-N3, M4-N8

M1-N5, M2-N1, M3-N4, M4-N8

M1-N8, M2-N1, M3-N4, M4-N5

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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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The equation of state for a non-ideal gas is

where P is pressure, v is specific volume, R is the specific gas constant, T is temperature, and B is a temperature dependent parameter. For this gas, the partial derivative of enthalpy with respect to pressure at constant temperature is

Your answerChoose one option.

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Consider the following data from a Brayton cycle.

Enthalpy at inlet to turbine: 1400 kJ/kg

Enthalpy at exit of turbine: 880 kJ/kg

Enthalpy at exit of compressor: 600 kJ/kg

On adding a regenerator of effectiveness equal to 0.8, the absolute value of percentage change in heat addition is ________ (rounded off to the nearest integer).

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An ideal gas undergoes a series of reversible steady state, steady flow processes between states 1, 2 and 3. Process 1→2 satisfies the relation

, where pressure, P is in kPa and specific volume, v is in m³/kg. Process 2→3 is isobaric. Given that

m³/kg,

, the total work done per unit mass (in kJ/kg) in the series of processes 1→2→3 is ________ (rounded off to the nearest integer).

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Air (assumed as an ideal gas) with a mass flow rate of 2.5 kg/s enters a horizontal nozzle at 350 K, 350 kPa with a velocity of 3 m/s. The air exits the nozzle at a pressure of 101.5 kPa and temperature 305 K with a Mach number of

. Assuming steady state operation and constant properties given in the data, the ratio of inlet area to exit area required to satisfy the exit condition is ________ (rounded off to one decimal place).

Use the following data:

kJ/kg.K,

kJ/kg.K

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The melting point of a substance at 1 bar is 273 K. The following property data is available for this substance at 1 bar.

Property	Value
Density of the solid phase	900 kg/m³
Density of the liquid phase	1000 kg/m³
Latent heat for melting	300 kJ/kg

Assuming that the above properties are constant, the melting point (in K) of the substance at 101 bar is ________ (rounded off to two decimal places).

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100 moles of moist air at 70% relative humidity is cooled from 70 °C to 50 °C at a constant pressure of 1 bar. The vapour pressures of water are given in the table. The number of moles of water left in the moist air at the end of this process is ________ (rounded off to two decimal places).

Temperature (°C)	Vapour Pressure (kPa)
50	12.34
70	31.16

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A rigid insulated tank containing an ideal gas at 300 K and 1 bar is being filled from an external pressurized line supplying the same gas at 300 K and 10 bar. When the mass of gas inside the tank has doubled, its temperature (in K) is ________ (rounded off to the nearest integer).

Assume ratio of specific heats to be constant for this process and equal to 1.4.

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GATE XE purpose:exam-prep PYQs

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