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: Thermal equilibrium

Question: For a cyclic process

• a)

  

• b)

  

• c) W = 0
• d) None of these

Answer:

Question: Select the incorrect relation. (Where symbols have their usual meanings)

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Internal energy of a non-ideal gas depends on

• a) All of these
• b) Volume
• c) Pressure
• d) Temperature

Answer: All of these

Question: For an adiabatic expansion of an ideal gas the fractional change in its pressure is equal to

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Which of the following laws of thermodynamics defines internal energy?

• a) First law
• b) Third law
• c) Second law
• d) Zeroth law

Answer: First law

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: All of these

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: 10.5 m

Question: Select the incorrect statement about the specific heats of a gaseous system

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: In following figures (a) to (d), variation of volume by change of pressure is shown in figure. The gas is taken along the path ABCDA. Change in internal energy of the gas will be

• a) Zero in all the four cases
• b) Negative in cases (a), (b) and (c) but zero in case (d)
• c) Positive in cases (a), (b) and (c) but zero in case (d)
• d) Positive in all cases from (a) to (d)

Answer: Zero in all the four cases

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: 18 J

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: On gas is 10⁵ J

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

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: All the above may change

Question:

• a) C – Isochoric process
• b) A – Isobaric process
• c) B – Adiabatic process
• d) D – Isothermal process

Answer:  C – Isochoric process

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

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:  12 J

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

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: dQ = +ve, dU = 0, dW = +ve

More Questions....................................

Question:

• a) –60 cal
• b) –30 cal
• c) 30 cal
• d) 60 cal

Answer: –60 cal

Question:

• a) 128 atm
• b) 32 atm
• c)

  

• d) 150 atm

Answer: 128 atm

Question: The adiabatic elasticity of a diatomic gas at NTP is

• a)

  

• b)

  

• c)

  

• d) 0

Answer:

Question: For an isometric process

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) 546°C
• b) 420°C
• c) 872°C
• d) 300°C

Answer:  546°C

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

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: Isobaric

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: The pressure and volume of a gas are changed as shown in the P-V diagram in this figure. The temperature of the gas will

• a) Increase as it goes from A to B
• b) Remain constant during these changes
• c) Increase as it goes from B to C
• d) Decrease as it goes from D to A

Answer: Increase as it goes from A to B

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

   

• d) W < 0

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) 0.3 J
• b) 4.5 J
• c) 1.5 J
• d) 1 J

Answer: 0.3 J

Question:  During which of the following thermodynamic process represented by PV diagram the heat energy absorbed by system may be equal to area under PV graph?

• a) All of these
• b)

  

• c)

  

• d)

  

Answer: All of these

Question: The specific heat of a gas in a polytropic process is given by

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  For a certain process, pressure of diatomic gas varies according to the relation P = aV², where a is constant. What is the molar heat capacity of the gas for this process?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) –200 R
• b) –100 R
• c) –400 R
• d) 200 R

Answer: –200 R

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: When heat is taken out from the system at constant temperature

Question:

• a) 2
• b) 1.5
• c) 1.67
• d) 2.1

Answer:  2

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer: