Thermodynamics — DPP 3

20 NEET questions from Thermodynamics, with answers and explanations. Attempt it as a timed test to get scoring, accuracy breakdown and mistake tracking.

Attempt this test free 20 questions · 30 minutes · +80 marks
1
A system is taken along the paths $A$ and $B$ as shown. If the amounts of heat given in these processes are $Q _ { \mathrm { A } }$ and $Q _ { \mathrm { B } }$ and change in internal energy are $\Delta U _ { \mathrm { A } }$ and $\Delta U _ { \mathrm { B } }$ respectively then;
Thermodynamics – NEET-11502
  1. A $Q _ { \mathrm { A } } = Q _ { \mathrm { B } } ; \Delta U _ { \mathrm { A } } < \Delta U _ { \mathrm { B } }$
  2. B $Q _ { \mathrm { A } } \geq Q _ { \mathrm { B } } ; \Delta U _ { \mathrm { A } } = \Delta U _ { \mathrm { B } }$
  3. C $Q _ { \mathrm { A } } < Q _ { \mathrm { B } } ; \Delta U _ { \mathrm { A } } > \Delta U _ { \mathrm { B } }$
  4. D $Q _ { \mathrm { A } } > Q _ { \mathrm { B } } ; \Delta U _ { \mathrm { A } } = \Delta U _ { \mathrm { B } }$
Show answer

Correct answer: D

2
Temperature is a measurement of coldness or hotness of an object. This definition is based on
  1. A Zeroth law of thermodynamics
  2. B First law of thermodynamics
  3. C Second law of thermodynamics
  4. D Newton's law of cooling
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Correct answer: A

3
Out of the following which quantity does not depend on path
  1. A Temperature
  2. B Heat
  3. C Work
  4. D Both (B) and (C)
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Correct answer: A

4
Which of the following is not a path function?
  1. A ΔW
  2. B ΔQ + ΔW
  3. C ΔQ - ΔW
  4. D ΔQ
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Correct answer: C

5
One kg of a diatomic gas is at pressure of $8 \times 10 ^ { 4 } \mathrm {~N} / \mathrm { m } ^ { 2 }$. The density of the gas is $4 \mathrm {~kg} / \mathrm { m } ^ { 3 }$. What is the energy of the gas due to thermal motion?
  1. A $3 \times 10 ^ { 4 } \mathrm {~J}$
  2. B $6 \times 10 ^ { 4 } \mathrm {~J}$
  3. C $5 \times 10 ^ { 4 } \mathrm {~J}$
  4. D $7 \times 10 ^ { 4 } \mathrm {~J}$
Show answer & explanation

Correct answer: C

Thermal energy corresponds to internal energy given:
Thermodynamics – NEET-11478 Therefore, option (C) is the correct answer.
6
Which of the following is incorrect regarding the first law of thermodynamics?
  1. A It introduces the concept of the internal energy
  2. B It introduces the concept of the entropy
  3. C It is not applicable to any cyclic process
  4. D Both (B) and (C)
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Correct answer: D

7
An ideal gas is taken through a cycle ABCA as shown in the P-V diagram. The work done during the cycle is:
Thermodynamics – NEET-11564
  1. A 2 PV
  2. B 3 PV
  3. C PV
  4. D PV/3
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Correct answer: C

8
If ΔΔQ, ΔE, and ΔW denote respectively the heat added, change in internal energy and the work done in a closed cyclic process then which of these will follow:
  1. A ΔW = 0
  2. B ΔQ = 0
  3. C ΔE = 0
  4. D ΔW = 0, ΔE = 0
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Correct answer: C

9
An ideal gas is taken around the cycle ABCA as shown in the figure, the work done by the gas during the cycle is
Thermodynamics – NEET-11568
  1. A 3 PV
  2. B 2 PV
  3. C PV
  4. D $\frac { 2 } { 3 } \mathrm { PV }$
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Correct answer: A

10
A cyclic process is shown in the figure. Work done during the cyclic process ABCDA is:
Thermodynamics – NEET-11566
  1. A 150 J
  2. B 163 J
  3. C 145 J
  4. D 166 J
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Correct answer: A

11
A monoatomic gas of n-moles is heated from temperature T$_{1}$ to T$_{2}$ under two different conditions (i) at constant volume and (ii) at constant pressure. The change in internal energy of the gas is
  1. A More for (i)
  2. B More for (ii)
  3. C Same in both cases
  4. D Independent of number of moles
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Correct answer: C

12
In a cyclic process, work done by the system is
  1. A $\Delta \mathrm { Q } = \Delta \mathrm { U } - \Delta \mathrm { W }$
  2. B $\Delta \mathrm { Q } = \Delta \mathrm { W }$
  3. C $- \Delta Q = \Delta U + \Delta W$
  4. D $\Delta Q = \Delta U$
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Correct answer: B

13
If temperature is increased by 1 K at constant volume then work done on the gas is:
  1. A Positive
  2. B Negative
  3. C Zero
  4. D Data Inadequate
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Correct answer: C

14
A gas is heated at constant pressure. The fraction of heat supplied used for external work is:
  1. A $1 - \frac { 2 } { \gamma }$
  2. B $1 - \frac { 3 } { \gamma }$
  3. C $1 - \frac { 2 } { 3 \gamma }$
  4. D $1 - \frac { 1 } { \gamma }$
Show answer

Correct answer: D

15
Heat is not being exchanged in a body. If its internal energy is increased, then
  1. A Its temperature will increase
  2. B Its temperature will decrease
  3. C Its temperature will remain constant
  4. D Its temperature may increase decrease and remains constant based on the process.
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Correct answer: A

16
A cylinder of fixed capacity 44.8 L contains 2 moles of He gas at STP. What is the amount of heat needed to raise the temperature of the gas in the cylinder by $20 ^ { \circ } \mathrm { C }$?
  1. A 496 J
  2. B 495 J
  3. C 502 J
  4. D 498 J
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Correct answer: D

17
A perfect gas contained in a cylinder is kept in vacuum. If the cylinder suddenly bursts, then the temperature of the gas
  1. A remains constant
  2. B becomes zero
  3. C increases
  4. D decreases
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Correct answer: A

18
The P-V diagram of a system undergoing thermodynamic transformation is shown in figure. The work done by the system in going from A → B → C is 30 joule, and 40 joule heat is given to the system. The change in Internal energy between A and C is:
Thermodynamics – NEET-11562
  1. A 70 Joule
  2. B 9 Joule
  3. C -10 Joule
  4. D 10 Joule
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Correct answer: D

19
Work done per mol in an isothermal change is
  1. A $R T \log _ { 10 } \frac { V _ { 2 } } { V _ { 1 } }$
  2. B $R T \log _ { 10 } \frac { V _ { 1 } } { V _ { 2 } }$
  3. C $R T \log _ { e } \frac { V _ { 2 } } { V _ { 1 } }$
  4. D $R T \log _ { e } \frac { V _ { 1 } } { V _ { 2 } }$
Show answer

Correct answer: C

20
In the diagrams (i) to (iv) of variation of volume with changing pressure is shown. A gas is taken along the path ABCDA. The change in internal energy of the gas will be;
Thermodynamics – NEET-11504 Thermodynamics – NEET-11504
  1. A Positive in all cases (i) to (iv)
  2. B Positive in cases (i), (ii) and (iii) but zero in case (iv)
  3. C Negative in cases (i), (ii) and (iii) but zero in case (iv)
  4. D Zero in all the four cases
Show answer

Correct answer: D

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