JEE Main 2021 · 24 February · morning · Single correct · +4 / −1

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

List IList II
(a)Isothermal(i)Pressure constant
(b)Isochoric(ii)Temperature constant
(c)Adiabatic(iii)Volume constant
(d)Isobaric(iv)Heat content is constant
  1. (1) (a) - (ii), (b) - (iii), (c) - (iv), (d) - (i)
  2. (2) (a) - (ii), (b) - (iv), (c) - (iii), (d) - (i)
  3. (3) (a) - (iii), (b) - (ii), (c) - (i), (d) - (iv)
  4. (4) (a) - (i), (b) - (iii), (c) - (ii), (d) - (iv)
Answer and solution

Answer (1) (a) - (ii), (b) - (iii), (c) - (iv), (d) - (i)

Solution

Physics sir · 3 steps

Read the Greek prefix and you have the answer: iso means same, and the root tells you what stays the same.

  1. Read the names. Iso means equal. Thermal is temperature, choric is volume (from the Greek for space) and baric is pressure (as in barometer). Adiabatic means no heat passes through.
    ProcessWhat stays fixedMatch
    (a) IsothermalTemperature, Δ T = 0(ii)
    (b) IsochoricVolume, Δ V = 0(iii)
    (c) AdiabaticNo heat exchanged, Q = 0(iv)
    (d) IsobaricPressure, Δ P = 0(i)
  2. Adiabatic check. In an adiabatic process the system is insulated, so Q = 0 and its heat content does not change. Its temperature can still change, because Δ U = -W.
  3. So. The matching is (a) - (ii), (b) - (iii), (c) - (iv), (d) - (i), which is option (1).

The idea to keep. Isothermal fixes T, isochoric fixes V, isobaric fixes P, and adiabatic fixes heat: Q = 0. Adiabatic does not mean constant temperature.

Answer from the NTA final answer key. Solution by PrepWiser.

Study Thermodynamics

Asked about 150 times in JEE Main since 2020. This question is from 2021.