A Carnot engine, having an efficiency of η =1/10 as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is
100 J
99 J
90 J
1 J
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The specific heat capacity of a metal at low temperature (T) is given as Cp(kJK–1kg–1) = 32$\left(\dfrac{\text{T}}{400}\right)^3$. A 100 gram vessel of this metal is to be cooled from 20 K to 4 K by a special refrigerator operating at room temperature (27°C). The amount of work required to cool the vessel is