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GATE 2019: Thermodynamics Quiz 4 (App update required to attempt this test)
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Question 1
During the quenching process, a hot iron of mass 25kg and at a temperature of 450oC is dropped in 180kg of oil at 20oC and having specific heat of 2.5 KJ/KgK. Assume specific heat of hot iron as 0.5 KJ/KgK .The entropy change (in KJ/K) of oil is
Question 2
A heat engine that receives heat from a furnace at 1500 K and rejects waste heat to river at 300 K, has a thermal efficiency of 40 percent. Second law efficiency (in %) of this engine is,
Question 3
1600 kJ of energy is transferred from a heat reservoir at 800 K to another heat reservoir at 400 K. The amount of entropy generated during the process would be (in kJ/K) __________.
Question 4
A 1000 Ω resistor carrying a current of 10 A for 2 sec is kept at a constant temperature of 27 °C by a stream of cooling water. Entropy change of the universe is ________ J/K.
Question 5
10 kg of ice at –13 °C is exposed to the atmosphere which is at 23 °C. The ice melts and comes into thermal equilibrium. Total entropy change of ice as it comes to thermal equilibrium with the environment is _____ kJ.
Cp of ice = 2.093 kJ/kg°C, Latent heat of fusion of ice = 333.33 kJ/kg.
Question 6
A sample is required to be maintained at the lowest possible temperature of 0.0014 K. The energy losses as heat from the sample is estimated 50 Watt and ambient temperature is 300 K. A reversible heat engine is used to drive the reversible refrigerator which uses a source at temperature 673 K and the ambient atmosphere as the sink.The energy absorbed (in MW) by the heat engine from the source in order to maintain the sample at the required temperature is ___.
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