428. According to Kelvin's Planck statement
A.It is impossible to construct a heat engine which operates in a cycle and receives a given amount of heat from a high temperature body and does equal amount of work
B.It is impossible to construct a device which operates in a cycle and produces no effect other than the transfer of heat from a cooler body to hotter body
C.When two dissimilar metals are heated at one end and cooled at other, e.m.f. is developed proportional to difference of temperatures at two ends
D.Heat can be converted into work
429. A steam nozzle converts
A.Kinetic energy into heat
B.Heat energy into kinetic energy
C.Potential energy into heat
D.Heat energy into useful energy
430. Which is true statement in connection with second law of thermodynamics?
A.It is not possible for the heat energy to flow spontaneously from a body at a lower temperature to a body at higher temperature
B.It is not possible to construct an engine, which while operating in a cycle produces no other effect except to extract heat from single reservoir and do equivalent amount of work.
C.Carnot engine as compared to all engines operating between given two temperature limits, is the most efficient
D.All of the above
431. According to Clausius statement
A.It is impossible to construct a heat engine which operates in a cycle and receives a given amount of heat from a high temperature body and does equal amount of work
B.It is impossible to construct a device which operates in a cycle and produces no effect other than the transfer of heat from cooler body to hotter body
C.When two dissimilar metals are heated at one end and cooled at other, e.m.f. is developed proportional to difference of temperatures at two ends
D.Heat can be converted into work
432. Under what condition it is possible that heat be abstracted from hot source, as well as cold source and positive work be done
A.Impossible
B.Hot reservoir is at negative temperature
C.Cold reservoir is at negative temperature
D.Both hot and cold reservoirs are at positive temperatures
433. What are the limitations to the signs of heat exchange form hot and cold reservoirs if a two-temperature machine operates between two positive temperatures
A.Heat must be rejected to hot source and abstracted from cold source
B.Heat must be abstracted from hot source and rejected to cold source
C.Heat must be rejected to both the sources
D.Heat must be abstracted from both the sources
434. Which is the wrong assumption for calculation of air standard efficiency
A.All processes are reversible
B.Specific heat remains constant at all temperatures
C.No account of the mechanism of heat transfer is considered
D.Gases dissociate at higher temperatures
Page 62 of 90