1
JEE Main 2021 (Online) 24th February Evening Slot
+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 Slot
+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 Slot
+4
-1
Match List I with List II.

List I List II
(a) Isothermal (i) Pressure constant
(b) Isochoric (ii) Temperature 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 Slot
+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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