Thermodynamics MCQs for NEET

(1) A thermodynamic system is explained with the help of the graph ABCD. What is the heat rejected by the system during the cycle?

[A] pV

[B] 2pV

[C] 4pV

[D] 1/2pV

Answer: 2pV

(2) What is the ratio of CpCv for gas if the pressure of the gas is proportional to the cube of its temperature and the process is an adiabatic process.

[A] 2

[B] 3/2

[C] 4/3

[D] 5/3

Answer: 3/2

(3) ABCDA is a cyclic process explaining the thermodynamic process. What is the work done by the system in the cycle

[A] Zero

[B] ρ₀V₀/2

[C] ρ₀V₀

[D] 2ρ₀V₀

Answer: ∞ , 0

(4) Which of the following process is used to do maximum work done on the ideal gas if the gas is compressed to half of its initial volume?

[A] Isothermal

[B] Isochoric

[C] Isobaric

[D] Adiabatic

Answer: Adiabatic

(5) Following is the diagram of the thermodynamic process. Refer the diagram and match the followings

P Process – I (a) Adiabatic

Q Process – II (b) Isobaric

R Process – III (c) Isochoric

S Process – IV (d) Isothermal

[A] (P,c), (Q,d), (R,b), (S,a)

[B] (P,c), (Q,d), (R,b), (S,a)

[C] (P,a), (Q,c), (R,d), (S,b)

[D] (P,c), (Q,a), (R,d), (S,b)

Answer: (P,c), (Q,a), (R,d), (S,b)

(6) An ideal gas heat engine operates in a Carnot cycle between 227oC and 127oC. It absorbs 6 kcal at the higher temperature. The amount of heat (in kcal) converted into work is equal to:

[A] 1.6

[B] 1.2

[C] 4.8

[D] 3.5

Answer: 1.2

(7) The temperature of reservoir of Carnots engine operating with an efficiency of 70% is 1000 kelvin. The temperature of its sink is

[A] 300 K

[B] 400 K

[C] 500 K

[D] 700 K

Answer: 300 K

(8) During an adiabatic process , the pressure of a gas is found to be proportional to the cube of its absolute temperature . The ratio Cp/Cv for the gas is

[A] 2

[B] 3/2

[C] 4/3

[D] 5/3

Answer: 3/2

(9) Starting with the same initial conditions, an ideal gas expands from volume V1 to V2 in three different ways. The work done by the gas is W1 if the process is purely isothermal; W2, if purely isobaric, and W3 ,if purely adiabatic. Then:

[A] W2 > W1 > W3

[B] W2 > W3 > W1

[C] W1 > W2 > W3

[D] W1 > W3 > W2

Answer: W2 > W1 > W3

(10) A gas at 300 K , enclosed in a container , is placed in a fast moving train . When the train is in motion , the temperature of the gas

[A] rises above 300 K

[B] falls below 300 K

[C] remains unchanged

[D] becomes unsteady

Answer: remains unchanged

(11) Directions: The following question has four choices out of which ONLY ONE is correct. Which of the following is incorrect regarding the first law of thermodynamics?

A. It is not applicable to any cyclic process

B. It is a restatement of the principle of conservation of energy

C. It introduces the concept of the internal energy

D. It introduces the concept of the entropy

[A] B and C

[B] C and A

[C] A and B

[D] curves representing an adiabatic process and an isothermal process don’t intersect.

Answer: B and C

(12) A gas is taken through a number of thermodynamic states. What happens to its specific heat?

[A] It is always constant.

[B] It increases.

[C] It decreases.

[D] It can have any value depending upon the process of heat absorbed or evolved.

Answer: It can have any value depending upon the process of heat absorbed or evolved.

(13) An ideal gas heat engine operates in Carnot cycle between 227°C and 127°C. It absorbs 6 x 104 cal of heat at higher temperature. Amount of heat converted to work is:

[A] 2.4 x 104 cal

[B] 6 x 104 cal

[C] 1.2 x 104 cal

[D] 4.8 x 104 cal

Answer: 1.2 x 104 cal

(14) The work of 62-25 KJ is performed in order to compress one kilo mole of gas adiabatically and in this process the temperature of the gas increases by 5C The gas is _______ R = 8-3 J/_molk

[A] triatomic

[B] monoatomic

[C] diatomic

[D] a mixture of monoatomic and diatomic

Answer: diatomic

(15) The internal energy change in a system that has absorbed 2 Kcal of heat and done 500J of work is

[A] 7900 J

[B] 4400 J

[C] 6400 J

[D] 8900 J

Answer: 7900 J

(16) The first law of thermodynamics is concerned with the conservation of

[A] momentum

[B] energy

[C] mass

[D] temperature

Answer: energy

(17) If heat given to a system is 6 k cal and work done is 6kj. The change in internal energy is _____KJ.

[A] 12.4

[B] 25

[C] 19.1

[D] 0

Answer: 19.1

(18) Which of the following is not a thermodynamical function.

[A] Enthalpy

[B] Work done

[C] Gibb's energy

[D] Internal energy

Answer: Work done

(19) In thesmodynamics, the work done by the system is considered ______ and the work done on the system is Considered _____

[A] Positive, zero

[B] nagative, Positive

[C] zero, negative

[D] Positive, negative

Answer: Positive, negative

(20) Heat capacity of a body depends on the _____ as well as on ______

[A] material of the body, its mass

[B] mass of the body, itd temperature

[C] material of the body, its temperature

[D] Volume of the body, its mass

Answer: material of the body, its mass

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