1
JEE Main 2025 (Online) 3rd April Morning Shift
MCQ (Single Correct Answer)
+4
-1
JEE Main 2025 (Online) 3rd April Morning Shift Physics - Heat and Thermodynamics Question 8 English

A piston of mass $M$ is hung from a massless spring whose restoring force law goes as $F=-k x^3$, where k is the spring constant of appropriate dimension. The piston separates the vertical chamber into two parts, where the bottom part is filled with ' $n$ ' moles of an ideal gas. An external work is done on the gas isothermally (at a constant temperature T) with the help of a heating filament (with negligible volume) mounted in lower part of the chamber, so that the piston goes up from a height $\mathrm{L}_0$ to $\mathrm{L}_1$, the total energy delivered by the filament is:(Assume spring to be in its natural length before heating)

A
$n R T \ln \left(\frac{L_1}{L_0}\right)+M g\left(L_1-L_0\right)+\frac{3 k}{4}\left(L_1{ }^4-L_0{ }^4\right)$
B
$n R T \ln \left(\frac{L_1}{L_0}\right)+M g\left(L_1-L_0\right)+\frac{k}{4}\left(L_1^4-L_0{ }^4\right)$
C
$n R T \ln \left(\frac{L_1^2}{L_0^2}\right)+\frac{M g}{2}\left(L_1-L_0\right)+\frac{k}{4}\left(L_1^4-L_0{ }^4\right)$
D
$3 n R T \ln \left(\frac{L_1}{L_0}\right)+2 M g\left(L_1-L_0\right)+\frac{k}{3}\left(L_1{ }^3-L_0{ }^3\right)$
2
JEE Main 2025 (Online) 2nd April Evening Shift
MCQ (Single Correct Answer)
+4
-1
$$ \text { Match List - I with List - II. } $$

$$ \begin{array}{lll} & \text { List - I } & {List - II }\\ \text { } \\ \text { (A) } & \text { Heat capacity of body } & \text { (I) } \mathrm{J} \mathrm{~kg}^{-1} \\ \text { (B) } & \text { Specific heat capacity of body } & \text { (II) } \mathrm{J} \mathrm{~K}^{-1} \\ \text { (C) } & \text { Latent heat } & \text { (III) } \mathrm{J} \mathrm{~kg}^{-1} \mathrm{~K}^{-1} \\ \text { (D) } & \text { Thermal conductivity } & \text { (IV) } \mathrm{J} \mathrm{~m}^{-1} \mathrm{~K}^{-1} \mathrm{~s}^{-1} \end{array} $$

$$ \text { Choose the correct answer from the options given below : } $$
A
(A)-(IV), (B)-(III), (C)-(II), (D)-(I)
B
(A)-(III), (B)-(I), (C)-(II), (D)-(IV)
C
(A)-(III), (B)-(IV), (C)-(I), (D)-(II)
D
(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
3
JEE Main 2025 (Online) 2nd April Evening Shift
MCQ (Single Correct Answer)
+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 $\mathrm{T}_1$ to $\mathrm{T}_2$ is proportional to $\left(\mathrm{T}_2-\mathrm{T}_1\right)$. Choose the correct answer from the options given below :
A
(B), (D) only
B
(B), (E) only
C
(A), (C), (E) only
D
(A), (C), (D) only
4
JEE Main 2025 (Online) 2nd April Morning Shift
MCQ (Single Correct Answer)
+4
-1

In an adiabatic process, which of the following statements is true?

A
The internal energy of the gas decreases as the temperature increases
B
The molar heat capacity is zero
C
Work done by the gas equals the increase in internal energy
D
The molar heat capacity is infinite
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