1
JEE Main 2020 (Online) 5th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Number of molecules in a volume of 4 cm3 of a perfect monoatomic gas at some temperature T and at a pressure of 2 cm of mercury is close to?
(Given, mean kinetic energy of a molecule
(at T) is 4 $$ \times $$ 10–14 erg, g = 980 cm/s2, density of
mercury = 13.6 g/cm3)
A
5.8 $$ \times $$ 1018
B
4.0 $$ \times $$ 1016
C
5.8 $$ \times $$ 1016
D
4.0 $$ \times $$ 1018
2
JEE Main 2020 (Online) 4th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Match the thermodynamic processes taking place in a system with the correct conditions. In the table : $$\Delta $$Q is the heat supplied, $$\Delta $$W is the work done and $$\Delta $$U is change in internal energy of the system.

Process Condition
(I) Adiabatic (1) $$\Delta $$W = 0
(II) Isothermal (2) $$\Delta $$Q = 0
(III) Isochoric (3) $$\Delta $$U $$ \ne $$ 0, $$\Delta $$W $$ \ne $$ 0, $$\Delta $$Q $$ \ne $$ 0
(IV) Isobaric (4) $$\Delta $$U = 0
A
(I) - (1), (II) - (1), (III) - (2), (IV) - (3)
B
(I) - (2), (II) - (4), (III) - (1), (IV) - (3)
C
(I) - (1), (II) - (2), (III) - (4), (IV) - (4)
D
(I) - (2), (II) - (1), (III) - (4), (IV) - (3)
3
JEE Main 2020 (Online) 4th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The specific heat of water
= 4200 J kg-1K-1 and the latent heat of
ice = 3.4 $$ \times $$ 105 J kg–1. 100 grams of ice at
0oC is placed in 200 g of water at 25oC. The
amount of ice that will melt as the temperature
of water reaches 0oC is close to (in grams) :
A
63.8
B
61.7
C
69.3
D
64.6
4
JEE Main 2020 (Online) 4th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Match the $${{{C_P}} \over {{C_V}}}$$ ratio for ideal gases with different type of molecules :

Molecule Type CP/CV
(A) Monatomic (I) 7/5
(B) Diatomic rigid molecules (II) 9/7
(C) Diatomic non-rigid molecules (III) 4/3
(D) Triatomic rigid molecules (IV) 5/3
A
(A)-(III), (B)-(IV), (C)-(II), (D)-(I)
B
(A)-(IV), (B)-(II), (C)-(I), (D)-(III)
C
(A)-(IV), (B)-(I), (C)-(II), (D)-(III)
D
(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
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