GATE ME
Thermodynamics
Entropy and Irreversibility
Previous Years Questions

Marks 1

Which one of the following pairs of equations describes an irreversible heat engine?
One kilogram of water at room temperature is brought into contact with a high temperature thermal reservoir. The entropy change of the universe is
If a closed system is undergoing an irreversible process, the entropy of the system
$$2$$ moles of oxygen are mixed adiabatically with another $$2$$ moles of oxygen in mixing chamber, so that the final total pressure and temperature o...
Which of the following relationships is valid only for reversible process undergone by a closed system of simple compressible substance (neglect chang...
For an ideal gas the expression $$\left[ {T{{\left( {{{\delta s} \over {\delta T}}} \right)}_p} - T{{\left( {{{\delta s} \over {\delta T}}} \right)}_v... A system undergoes a state change from$$1$$to$$2.$$According to the second law of thermodynamics, for the process to be feasible, the entropy chan... A$$1500W$$electrical heater is used to heat$$20kg$$of water$$\left( {{C_p} = 4186\,\,J/kg\,\,K} \right)$$in an insulated bucket, from ... The slopes of constant volume and constant pressure lines in the$$T$$-$$s$$diagram are ___________ and ___________respectively. When a system executes an irreversible cycle: Which among the following relations is/are valid ONLY for reversible process undergone by a pure substance? Marks 2 One$$kg$$of an ideal gas (gas constant$$R=287J/kg$$-$$K$$) undergoes an irreversible process from state-$${\rm I}$$($$1$$bar,$$300K$... One kg of air ($${R = 287\,\,J/kg}$$-$$K$$) under goes irreversible process between equilibrium state $$1\,\,\left( {{{20}^ \circ }C,\,\,0.9\,\,{m^3}}... A closed system contains$$10kg$$of saturated liquid ammonia at$${10^ \circ }C.$$Heat addition required to convert the entire liquid into satu... Two identical metal blocks$$L$$and$$M$$(specific heat$$=0.4kJ/kg.K$$), each having a mass of$$5kg,$$are initially at$$313K.$$A... An amount of$$100kW$$of heat is transferred through a wall in steady state. One side of the wall is maintained at$${127^ \circ }C$$and the ot... An ideal gas of mass$$m$$and temperature$${T_1}$$undergoes a reversible isothermal process from an initial pressure$${P_1}$$to final pressure$$... In an experimental set-up, air flows between two stations $$P$$ and $$Q$$ adiabatically. The direction of flow depends on the pressure and temperature... In an experimental set-up, air flows between two stations $$P$$ and $$Q$$ adiabatically. The direction of flow depends on the pressure and temperature... Consider the following two processes; $$\left( {\rm I} \right)$$ A heat source at $$1200$$ $$K$$ loses $$2500$$ $$kJ$$ of heat to a sink at $$800$$$...
A cycle device operates between three thermal reservoirs, as shown in the figure. Heat is transferred to/from the cyclic device. It is assumed that he...
A vapor absorption refrigeration system is a heat pump with three thermal reservoirs as shown in the figure. A refrigeration effect of $$100$$ $$W$$ i...
Considering the relationship $$TdS=dU+PdV$$ between the entropy $$(S),$$ internal energy $$(U),$$ pressure $$(P),$$temperature $$(T)$$ and volume $$(V... Nitrogen gas (molecular weight$$28$$) is enclosed in a cylinder by a piston, at the initial condition of$$2$$bar,$$298K$$and$$1\,\,{m^3}$$.... Nitrogen gas (molecular weight$$28$$) is enclosed in a cylinder by a piston, at the initial condition of$$2$$bar,$$298K$$and$$1\,\,{m^3}$$.... One kilomole of an ideal gas is throttled from an initial pressure of$$0.5MPa$$to$$0.1MPa.$$The initial temperature is$$300K.$$Th... Figure below shows a reversible heat engine$${E_R}$$having heat interactions with three constant temperature systems. Calculate the thermal efficien... Marks 5 An iron cube at a temperature of$$400$$deg$$C$$is dropped into an insulated bath containing$$10kg$$water at$${25^ \circ }C. The water fi...
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