Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Heat and Thermodynamics question

2025 · 2 Apr · Shift 2 · Q68
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Physics
  4. /Heat and Thermodynamics
  5. /2025 · 2 Apr · Shift 2 · Q68

Heat and Thermodynamics question

2025 · 2 Apr · Shift 2 · Q68

JEE MainPhysicsHeat and ThermodynamicsMCQ+4 / −1
Identify the characteristics of an adiabatic process in a monoatomic gas. (A) Internal energy is constant. (B) Work done in the process is equal to the change in internal energy. (C) The product of temperature and volume is a constant. (D) The product of pressure and volume is a constant. (E) The work done to change the temperature from T1\mathrm{T}_1T1​ to T2\mathrm{T}_2T2​ is proportional to (T2−T1)\left(\mathrm{T}_2-\mathrm{T}_1\right)(T2​−T1​). Choose the correct answer from the options given below :
  1. A
    (B), (D) only
  2. B
    (B), (E) only
  3. C
    (A), (C), (E) only
  4. D
    (A), (C), (D) only
View written solutionFree

Correct answer: B

  1. Adiabatic process condition

    For an adiabatic process, Q=0Q=0Q=0

    Using the first law of thermodynamics, ΔQ=ΔU+W\Delta Q = \Delta U + WΔQ=ΔU+W where WWW is the work done by the gas.

    Since Q=0Q=0Q=0, 0=ΔU+W  ⟹  W=−ΔU0=\Delta U + W \implies W=-\Delta U0=ΔU+W⟹W=−ΔU

    In magnitude, the work done is equal to the change in internal energy. Thus statement (B) is taken as correct in the usual exam convention.

  2. Check statement (A): Internal energy is constant

    For a monoatomic ideal gas, U=32nRTU=\frac{3}{2}nRTU=23​nRT So internal energy depends only on temperature. In an adiabatic process, temperature generally changes, so internal energy is not constant.

    Hence (A) is false.

  3. Check statement (C): Product of temperature and volume is constant

    For an adiabatic process of an ideal gas, PVγ=constantPV^\gamma=\text{constant}PVγ=constant and also TVγ−1=constantTV^{\gamma-1}=\text{constant}TVγ−1=constant

    For a monoatomic gas, γ=53\gamma=\frac{5}{3}γ=35​ so TV2/3=constantTV^{2/3}=\text{constant}TV2/3=constant not TV=constantTV=\text{constant}TV=constant.

    Hence (C) is false.

  4. Check statement (D): Product of pressure and volume is constant

    PV=constantPV=\text{constant}PV=constant is true for an isothermal process, not adiabatic.

    In adiabatic process, PVγ=constantPV^\gamma=\text{constant}PVγ=constant

    Hence (D) is false.

  5. Check statement (E): Work done to change temperature from T1T_1T1​ to T2T_2T2​ is proportional to (T2−T1)(T_2-T_1)(T2​−T1​)

    For a monoatomic ideal gas, ΔU=nCV(T2−T1)\Delta U = nC_V(T_2-T_1)ΔU=nCV​(T2​−T1​) where CV=3R2C_V=\frac{3R}{2}CV​=23R​

    In an adiabatic process, W=−ΔU=−nCV(T2−T1)W=-\Delta U=-nC_V(T_2-T_1)W=−ΔU=−nCV​(T2​−T1​)

    Therefore work done is indeed proportional to (T2−T1)(T_2-T_1)(T2​−T1​).

    Hence (E) is true.

  6. Conclusion

    Correct statements are: (B),(E)\boxed{(B), (E)}(B),(E)​

    Therefore the correct option is B\boxed{\text{B}}B​

PreviousNext

More from Heat and Thermodynamics

  • The internal energy of air in 4 m×4 m×3 m sized room at 1 atmospheric pressure will be ​×106 J (Consider air as diatomic molecule)2025 · Numerical
  • A gas is kept in a container having walls which are thermally non-conducting. Initially the gas has a volume of 800 cm3 and temperature 27∘C. The change in temperature when the gas is adiabatically…2025 · MCQ
  • During the melting of a slab of ice at 273 K at atmospheric pressure :2025 · MCQ
  • A piston of mass M is hung from a massless spring whose restoring force law goes as F=−kx3, where k is the spring constant of appropriate dimension. The piston separates the vertical chamber into two parts, where the bottom part is… Includes diagram2025 · MCQ
  • An ideal gas exists in a state with pressure P0​, volume V0​. It is isothermally expanded to 4 times of its initial volume (V0​), then isobarically compressed to its original volume. Finally the system is heated…2025 · MCQ
  • Pressure of an ideal gas, contained in a closed vessel, is increased by 0.4% when heated by 1∘C. Its initial temperature must be:2025 · MCQ
  • Consider the sound wave travelling in ideal gases of He,CH4​, and CO2​. All the gases have the same ratio ρP​, where P is the pressure and ρ is the density. The ratio of the speed of…2025 · MCQ
  • The mean free path and the average speed of oxygen molecules at 300 K and 1 atm are 3×10−7 m and 600 m/s, respectively. Find the frequency of its collisions.2025 · MCQ