1
JEE Main 2021 (Online) 25th February Morning Slot
+4
-1
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A : When a rod lying freely is heated, no thermal stress is developed in it.

Reason R : On heating, the length of the rod increases.

In the light of the above statements, choose the correct answer from the options given below :
A
A is true but R is false
B
A is false but R is true
C
Both A and B are true but R is NOT the correct explanation of A
D
Both A and R are true and R is the correct explanation of A
2
JEE Main 2021 (Online) 25th February Morning Slot
+4
-1
A diatomic gas, having $${C_p} = {7 \over 2}R$$ and $${C_v} = {5 \over 2}R$$, is heated at constant pressure. The ratio dU : dQ : dW :
A
5 : 7 : 3
B
3 : 7 : 2
C
5 : 7 : 2
D
3 : 5 : 2
3
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
$$0$$
4
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.
JEE Main Subjects
Physics
Mechanics
Electricity
Optics
Modern Physics
Chemistry
Physical Chemistry
Inorganic Chemistry
Organic Chemistry
Mathematics
Algebra
Trigonometry
Coordinate Geometry
Calculus
EXAM MAP
Joint Entrance Examination
GATE CSEGATE ECEGATE EEGATE MEGATE CEGATE PIGATE IN
Medical
NEET