GATE XE year:2017 PYQs & Answers — Page 10

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

A heat engine receives

kJ of heat from a hot reservoir and rejects

kJ of heat to a cold reservoir. The work delivered by the heat engine is entirely supplied to a heat pump, which receives

kJ of heat from another reservoir and rejects

kJ of heat to the same cold reservoir. If the efficiency of the heat engine is 0.4 and COP of the heat pump is 4.0, the value of

(up to 1 decimal place) is _________.

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A block of ice of mass 2 kg at 0°C is dropped into an insulated vessel containing 10 kg of liquid water at 25°C. The latent heat of melting of ice is 330 kJ/kg and specific heat of water is 4.2 kJ/kg.K. The change in the entropy of the universe in kJ/K (up to 3 decimal places) is _________.

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A pure substance (

= 0.733 kJ/kg.K) undergoes a reversible process in which its temperature increases linearly from 40°C to 85°C and its specific entropy increases by 600 J/kg.K. The work done by the system in kJ/kg is

Your answerChoose one option.

160.2

164.3

168.3

172.3

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An ideal gas having a mass of 0.5 kg is initially at 300 kPa, 80°C and occupies a volume of 0.14 m³. The gas undergoes an adiabatic process, where 50 kJ of work is transferred to the gas. The pressure and volume at the final state are 300 kPa and 0.20 m³. The change in the entropy of the gas in J/K is

Your answerChoose one option.

160.3

175.3

190.3

195.3

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The van der Waals equation of state is given as,

where p in bar, v in m³/kmol and T is in K. For air, the constants, a and b, are 1.368 bar.(m³/kmol)² and 0.0367 m³/kmol, respectively. Air is contained in a system at 160 K and 0.08 m³/kmol. If p₁ is the pressure calculated using ideal gas equation of state and p₂ is pressure calculated using van der Waals equation of state, then p₁/p₂ is equal to

Your answerChoose one option.

1.78

1.52

1.28

1.0

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The values of specific volume of H₂O at 100°C for saturated liquid and saturated vapor states are 0.00104 m³/kg and 1.673 m³/kg, respectively. The slope of saturation pressure versus temperature curve, i.e.,

is 3570 Pa/K. The change in enthalpy in kJ/kg between the two saturation states is _________.

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In a steam power plant, steam is first expanded isentropically in a turbine from an initial condition of 100 bar and 500 °C to a pressure of 40 bar. Then the steam is reheated up to 500 °C at constant pressure. The steam is then expanded isentropically in another turbine up to a condenser pressure 0.01 bar. For steam, at 100 bar, 500°C: h = 3373.7 kJ/kg, s = 6.596 kJ/kg.K; at 40 bar, 500°C: h = 345.3 kJ/kg, s = 7.091 kJ/kg.K and at 0.01 bar: h_f = 29.3 kJ/kg, h_g = 2514.2 kJ/kg, s_f = 0.1059 kJ/kg.K, s_g = 8.9756 kJ/kg.K. The dryness fraction at the condenser inlet (up to 2 decimal places) is _________.

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Air contains by volume 79% N₂ (molecular weight = 28 kg/kmol) and 21% O₂ (molecular weight = 32 kg/kmol). A stream of air flows at 32°C, 1 bar, at a rate of 2 m³/s and is mixed with another stream of O₂ flowing at 0.4 kg/s. The molecular weight of the mixture (up to 2 decimal places) is _________.

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Moist air enters a duct at a rate of 3 kg/s at 10°C, 80% relative humidity. The air is heated as it flows through the duct and exits at 30°C. No moisture is added or removed and the pressure of air in the duct is constant at 1 bar. The saturation vapor pressure (p_g) of H₂O at 10°C is 0.01228 bar. Specific enthalpy values of dry air at inlet and outlet of the duct are respectively 283.1 kJ/kg and 303.2 kJ/kg. The corresponding specific enthalpy values for water vapor are 2519.8 kJ/kg and 2556.3 kJ/kg. For steady state operation the amount of heat added to the moist air in kW (up to 2 decimal places) is _________.

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Poly(ethylene terephthalate) is synthesized from

Your answerChoose one option.

Ethylene + dimethyl terephthalate

Ethylene + terephthalic acid

Glycerol + terephthalic acid

Ethylene Glycol + terephthalic acid

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GATE XE year:2017 PYQs

Question 91

Question 92

Question 93

Question 94

Question 95

Question 96

Question 97

Question 98

Question 99

Question 100