1
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
$$nRT\left( {\ln 2 + {1 \over 2}} \right)$$
2
JEE Main 2021 (Online) 24th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Each side of a box made of metal sheet in cubic shape is 'a' at room temperature 'T', the coefficient of linear expansion of the metal sheet is '$$\alpha$$'. The metal sheet is heated uniformly, by a small temperature $$\Delta$$T, so that its new temperature is T + $$\Delta$$T. Calculate the increase in the volume of the metal box.
A
3a3$$\alpha$$$$\Delta$$T
B
4$$\pi$$a3$$\alpha$$$$\Delta$$T
C
$${{4 \over 3}}$$$$\pi$$a3$$\alpha$$$$\Delta$$T
D
4a3$$\alpha$$$$\Delta$$T
3
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
In a dilute gas at pressure P and temperature T, the mean time between successive collisions of a molecule varies with T as :
A
$$\sqrt T$$
B
T
C
$${1 \over T}$$
D
$${1 \over {\sqrt T }}$$
4
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Three rods of identical cross-section and lengths are made of three different materials of thermal conductivity K1 , K2 and K3 , respecrtively. They are joined together at their ends to make a long rod (see figure). One end of the long rod is maintained at 100oC and the other at 0oC (see figure). If the joints of the rod are at 70oC and 20oC in steady state and there is no loss of energy from the surface of the rod, the correct relationship between K1 , K2 and K3 is :
A
K1 : K3 = 2 : 3,
K2 : K3 = 2 : 5
B
K1 < K2 < K3
C
K1 : K2 = 5 : 2,
K1 : K3 = 3 : 5
D
K1 > K2 > K3
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