JEE Physics Thermodynamics MCQs Set A

Question. In thermodynamics the Zeroth law is related to
(a) Thermal equilibrium
(b) Entropy
(c) Diffusion
(d) Work done

Answer: A

Question. Internal energy of a non-ideal gas depends on
(a) All of these
(b) Volume
(c) Pressure
(d) Temperature

Answer: A

Question. Which of the following laws of thermodynamics defines internal energy?
(a) First law
(b) Third law
(c) Second law
(d) Zeroth law

Answer: A

Question. Select the correct statement for work, heat and change in internal energy.
(a) All of these
(b) Heat and work depend on the path between the two points
(c) Change in internal energy depends on the initial and final states only
(d) Heat supplied and work done depend on initial and final states

Answer: A

Question. Morning breakfast gives 5000 cal to a 60 kg person. The efficiency of person is 30%. The height upto which the person can climb up by using energy obtained from breakfast is
(a) 10.5 m
(b) 15 m
(c) 16.5 m
(d) 5 m

Answer: D

Question. In a thermodynamic process pressure of a fixed mass of a gas is changed in such a manner that the gas releases 20 J of heat when 8 J of work was done on the gas. If the initial internal energy of the gas was 30 J, then the final internal energy will be
(a) 18 J
(b) 2 J
(c) 42 J
(d) 58 J

Answer: A

Question. A perfect gas goes from state A to state B by absorbing 8 × 10⁵ joule and doing 6.5 × 10⁵ joule of external work. If it is taken from same initial state A to final state B in another process in which it absorbs 10⁵ J of heat, then in the second process work done
(a) On gas is 10⁵ J
(b) By gas is 10⁵ J
(c) On gas is 0.5 × 10⁵ J
(d) By gas is 0.5 × 10⁵ J

Answer: A

Question. A gas undergoes a change at constant temperature. Which of the following quantities remain fixed?
(a) All the above may change
(b) Entropy
(c) Pressure
(d) Heat exchanged with the system

Answer: A

Question. A certain amount of an ideal monatomic gas needs 20 J of heat energy to raise its temperature by 10°C at constant pressure. The heat needed for the same temperature rise at constant volume will be
(a) 12 J
(b) 30 J
(c) 200 J
(d) 215.3 J

Answer: A

Question. A sample of an ideal gas undergoes an isothermal expansion. If dQ, dU and dW represent the amount of heat supplied, the change in internal energy and the work done respectively, then
(a) dQ = +ve, dU = 0, dW = +ve
(b) dQ = –ve, dU = –ve, dW = –ve
(c) dQ = +ve, dU = +ve, dW = +ve
(d) dQ = +ve, dU = +ve, dW = 0

Answer: A

Question. In which process P-V diagram is a straight line parallel to the volume axis?
(a) Isobaric
(b) Isothermal
(c) Adiabatic
(d) Isochoric

Answer: A

Question. Entropy of a system decreases
(a) When heat is taken out from the system at constant temperature
(b) When heat is supplied to a system at constant temperature
(c) At equilibrium
(d) In any spontaneous process

Answer: A