1
JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
If one mole of an ideal gas at (P1, V1) is allowed to expand reversibly and isothermally (A to B) its pressure is reduced to one-half of the original pressure (see figure). This is followed by a constant volume cooling till its pressure is reduced to one-fourth of the initial value (B $$\to$$ C). Then it is restored to its initial state by a reversible adiabatic compression (C to A). The net workdone by the gas is equal to :

A
$$- {{RT} \over {2(\gamma - 1)}}$$
B
$$RT\left( {\ln 2 - {1 \over {2(\gamma - 1)}}} \right)$$
C
$$RT\ln 2$$
D
$$0$$
2
JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
On the basis of kinetic theory of gases, the gas exerts pressure because its molecules :
A
continuously lose their energy till it reaches wall.
B
are attracted by the walls of container.
C
suffer change in momentum when impinge on the walls of container.
D
continuously stick to the walls of container.
3
JEE Main 2021 (Online) 24th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Match List I with List II.

List I List II
(a) Isothermal (i) Pressure constant
(b) Isochoric (ii) Temperature constant
(c) Adiabatic (iii) Volume constant
(d) Isobaric (iv) Heat content is constant

Choose the correct answer from the options given below :
1
(a) - (ii), (b) - (iii), (c) - (iv), (d) - (i)
2
(a) - (ii), (b) - (iv), (c) - (iii), (d) - (i)
3
(a) - (iii), (b) - (ii), (c) - (i), (d) - (iv)
4
(a) - (i), (b) - (iii), (c) - (ii), (d) - (iv)
4
JEE Main 2021 (Online) 24th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
n mole of a perfect gas undergoes a cyclic process ABCA (see figure) consisting of the following processes.

A $$\to$$ B : Isothermal expansion at temperature T so that the volume is doubled from V1 to V2 = 2V1 and pressure charges from P1 to P2

B $$\to$$ C : Isobaric compression at pressure P2 to initial volume V1.

C $$\to$$ A : Isochoric change leading to change of pressure from P2 to P1.

Total workdone in the complete cycle ABCA is :

A
nRTln 2
B
0
C
$$nRT\left( {\ln 2 - {1 \over 2}} \right)$$
D
$$nRT\left( {\ln 2 + {1 \over 2}} \right)$$
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