Learn

Saturday, 31 October

JEE Main 2024 · PhysicsMultiple choiceDiagram basedHardConceptual

JEE Main 30 January 2024, Shift 1, Physics Q38

Question 38 of 90 in this shift, Physics question 8 of 30, Section A.

Two thermodynamical processes are shown in the figure. The molar heat capacity for process A and B are CAC_A and CBC_B. The molar heat capacity at constant pressure and constant volume are represented by CPC_P and CVC_V, respectively. Choose the correct statement.

The figure, in words

log P (vertical) versus log V (horizontal) graph; two straight lines from origin O, process A steeper with slope marked tan^-1 gamma, process B at 45 degrees; arrows pointing away from O along each line.
  1. (1)CA>CP>CVC_A > C_P > C_V
  2. (2)CP>CV>CA=CBC_P > C_V > C_A = C_B
  3. (3)CA=0C_A = 0 and CB=∞C_B = \inftyOfficial answer
  4. (4)CB=∞, CA=0C_B = \infty,\ C_A = 0Official answer

Official answer

Options 3 and 4

NTA final key: multiple options accepted. Either option scored full marks.

Chapter
Thermodynamics
Topic
Thermodynamic Processes
Idea tested
Polytropic Process Analysis

Same idea in other shifts

Asked 5× in all
  1. 1 Feb 2024, Shift 1 · Q38The pressure and volume of an ideal gas are related as PV32=KPV^{\frac{3}{2}} = K (Constant). The work done when the gas is taken from state A…MediumSingle correct
  2. 25 Feb 2021, Shift 1 · Q29In a certain thermodynamical process, the pressure of a gas depends on its volume as kV3kV^{3}. The work done when the temperature changes…MediumNumerical value
  3. 25 Feb 2021, Shift 2 · Q5Thermodynamic process is shown below on a P-V diagram for one mole of an ideal gas. If V2=2V1V_2 = 2V_1 then the ratio of temperature…EasyDiagram basedHas a figure
  4. 26 Feb 2021, Shift 2 · Q23The volume V of a given mass of monoatomic gas changes with temperature T according to the relation V = KT23T^{\frac{2}{3}}. The workdone…MediumNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.