GATE XE year:2018 PYQs & Answers — Page 10

Questions 91–100 of 175. Imported answers require independent review unless marked reviewed.

Topic practice 175 questionsPage 10 of 18

For a refrigerator absorb heat

from a cold region and rejecting heat

to a hot region, the coefficient of performance is written as

Your answerChoose one option.

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The value of the compressibility factor at the critical point evaluated using the van der Waals equation of state is

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The vapour pressure of a liquid at 8 °C is 2.7 kPa. Its enthalpy of vaporization is constant and equal to 4700 kJ/kmol. Take R = 8.314 kJ/kmol.K. The temperature (in °C) at a vapour pressure of 13.5 kPa is

Your answerChoose one option.

58.7

51.4

44.3

35.2

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One kmol of an ideal gas (C

= 21 kJ/kmol.K) undergoes a constant pressure process from 300 K to 500 K. The molar entropy of the gas at 300 K is 150 kJ/kmol.K. The molar entropy (in kJ/kmol.K) at 500 K (up to 1 decimal place) is ________.

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A spring, having a spring constant of 350 kN/m, is initially compressed by 0.4 cm. The work required (in J) to compress it by another 0.6 cm (up to 1 decimal place) is ________.

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An ideal gas has a molar mass of 40 kg/kmol. Take R = 8.314 kJ/kmol.K. At a pressure of 2 bar and a temperature of 300 K, the volume (in m

) of 1 kg of this gas (up to 2 decimal places) is ________.

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Consider the following statements for an ideal gas undergoing a reversible non-flow process: P. If the process is adiabatic, the change in enthalpy of the gas is necessarily zero. Q. If the process is adiabatic, the change in entropy of the gas is necessarily zero. R. If the process is isothermal, the change in enthalpy of the gas is necessarily zero. S. If the process is isothermal, the change in entropy of the gas is necessarily zero.

Which one of the following options is valid?

Your answerChoose one option.

Only P is correct

Only S is correct

Only Q and R are correct

Only P and S are correct

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An ideal Otto cycle (O) and an ideal diesel cycle (D) have the same maximum temperature and reject equal amount of heat. Also, the working fluid enters at the same state before compression. One of the following statements always true about their efficiencies (

) is

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A reversible engine receives 75 kJ/s of energy from a reservoir at 750 K and does 12 kJ/s of work. The heat is rejected to two reservoirs at 650 K and 550 K. The rate of heat rejection (in kJ/s) to the reservoir at 650 K is

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A gas obeys the following equation of state:

where

is molar volume, and

are constants with values

J.K/Pa

.kmol and

/kmol. Take

kJ/kmol.K. At 10 bar and 500 K, the value of the Joule-Thomson coefficient (in K/Pa) is

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GATE XE year:2018 PYQs

Question 4

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Question 11

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Question 13