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

• 99 J

• 90 J

• 1 J

• 100 J

Two moles of helium gas are taken over the cycle ABCDA, as shown in the P–T diagram. 



Assuming the gas to be ideal the work done on the gas in taking it from A to B is

When a system is taken from state i to state f along the path iaf, it is found that Q = 50 cal and W = 20 cal. Along the path’ ibf Q = 36 cal. W along the path ibf is

The work of 146 kJ is performed in order to compress one kilo mole of gas adiabatically and in this process the temperature of the gas increases by 7° C. The gas is

(R = 8.3 J mol⁻¹ K⁻¹ )

Which of the following is incorrect regarding the first law of thermodynamics?

A system goes from A to B via two processes I and II as shown in the figure. If ∆U₁ and ∆U₂ are the changes in internal energies in the processes I and II respectively, the

Which of the following statements is correct for any thermodynamic system?