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Thermodynamics (Physics) · Question 12

JEE Main 2026 (Online) 24th January Morning ShiftMCQMedium📈 Topic in 13% papers+4−1
1

Densities of water at 4 and 20 are 1000 kg/m3 and 998 kg/m3 respectively. The increase in internal energy of 4 kg of water when it is heated from 4 to 20 is J. (specific heat capacity of water = 4.2 kJ/kg K and 1 atmospheric pressure = 105 Pa)

  1. 268799.2
  2. 315826.2
  3. 234699.2
  4. 258700.8

Answer

(1) 268799.2

Solution

Heat supplied: Q = mc T = 4 4200 16 = 268800 J

Volumes: V1 = 41000 = 4 10-3 m3, V2 = 4998 = 4.008016 10-3 m3

V = 8.016 10-6 m3

Work done by water at atmospheric pressure: W = P V = 105 8.016 10-6 = 0.8016 J

First law: U = Q - W = 268800 - 0.8016

U 268799.2 J

Answer: (1)

JEE Main 2026 (Online) 24th January Morning Shift

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2

10 mole of an ideal gas is undergoing the process shown in the figure. The heat involved in the process from P1 to P2 is Joule (P1 = 21.7 Pa and P2 = 30 Pa, Cv = 21 J/K mol, R = 8.3 J/mol K). The value of is . [figure]

  1. 21
  2. 28
  3. 24
  4. 15
JEE Main 2026 (Online) 24th January Evening Shift
3

When 300 J of heat is given to an ideal gas with Cp = 72R, its temperature rises from 20 to 50 keeping its volume constant. The amount of the gas is (approximately) 10-3 mol. (R = 8.314 J/mol K)

JEE Main 2026 (Online) 24th January Evening Shift
4

One mole of an ideal diatomic gas expands from volume V to 2V isothermally at a temperature 27 and does W joule of work. If the gas undergoes same magnitude of expansion adiabatically from 27 doing the same amount of work W, then its final temperature will be (close to) . ( e 2 = 0.693)

  1. -56
  2. -117
  3. -30
  4. -189
JEE Main 2026 (Online) 23rd January Evening Shift
5

The internal energy of a monoatomic gas is 3nRT. One mole of helium is kept in a cylinder having internal cross section area of 17 cm2 and fitted with a light movable frictionless piston. The gas is heated slowly by supplying 126 J heat. If the temperature rises by 4 , then the piston will move cm. (atmospheric pressure = 105 Pa)

  1. 1.55
  2. 14.5
  3. 15.5
  4. 1.45
JEE Main 2026 (Online) 23rd January Evening Shift
6

The volume of an ideal gas increases 8 times and temperature becomes (1/4)th of initial temperature during a reversible change. If there is no exchange of heat in this process ( Q = 0) then identify the gas from the following options (Assuming the gases given in the options are ideal gases) :

  1. NH3
  2. O2
  3. CO2
  4. He
JEE Main 2026 (Online) 22nd January Morning Shift
7

10 mole of oxygen is heated at constant volume from 30 to 40 . The change in the internal energy of the gas is cal. (The molecular specific heat of oxygen at constant pressure, CP = 7 cal/mol C and R = 2 cal/mol C.)

JEE Main 2026 (Online) 21st January Morning Shift
8

A diatomic gas ( = 1.4) does 100 J of work when it is expanded isobarically. Then the heat given to the gas J.

JEE Main 2026 (Online) 21st January Evening Shift
9

A monoatomic gas having = 53 is stored in a thermally insulated container and the gas is suddenly compressed to ( 18 )th of its initial volume. The ratio of final pressure and initial pressure is: ( is the ratio of specific heats of the gas at constant pressure and at constant volume)

  1. 16
  2. 32
  3. 28
  4. 40
JEE Main 2025 (Online) 8th April Evening Shift
10

An ideal gas has undergone through the cyclic process as shown in the figure. Work done by the gas in the entire cycle is 10-1 J. (Take = 3.14) [figure]

JEE Main 2025 (Online) 7th April Morning Shift
11

Match List - I with List - II. Choose the correct answer from the options given below :

  1. A-III, B-II, C-I, D-IV
  2. A-II, B-IV, C-I, D-III
  3. A-IV, B-II, C-III, D-I
  4. A-IV, B-I, C-III, D-II
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