1
JEE Main 2019 (Online) 9th April Evening Slot
+4
-1
50 W/m2 energy density of sunlight is normally incident on the surface of a solar panel. Some part of incident energy (25%) is reflected from the surface and the rest is absorbed. The force exerted on 1m2 surface area will be close to (c = 3 × 108 m/s) :-
A
20 × 10–8 N
B
35 × 10–8 N
C
10 × 10–8 N
D
15 × 10–8 N
2
JEE Main 2019 (Online) 9th April Evening Slot
+4
-1
The specific heats, CP and CV of a gas of diatomic molecules, A, are given (in units of J mol–1 K–1) by 29 and 22, respectively. Another gas of diatomic molecules, B, has the corresponding values 30 and 21. If they are treated as ideal gases, then :-
A
A is rigid but B has a vibrational mode
B
A has a vibrational mode but B has none
C
A has one vibrational mode and B has two
D
Both A and B have a vibrational mode each
3
JEE Main 2019 (Online) 9th April Morning Slot
+4
-1
An HCl molecule has rotational, translational and vibrational motions. If the rms velocity of HCl molecules in its gaseous phase is $$\overline v$$ , m is its mass and kB is Boltzmann constant, then its temperature will be :
A
$${{m{{\overline v }^2}} \over {5{k_B}}}$$
B
$${{m{{\overline v }^2}} \over {6{k_B}}}$$
C
$${{m{{\overline v }^2}} \over {7{k_B}}}$$
D
$${{m{{\overline v }^2}} \over {3{k_B}}}$$
4
JEE Main 2019 (Online) 9th April Morning Slot
+4
-1
Following figure shows two processes A and B for a gas. If $$\Delta$$QA and $$\Delta$$QB are the amount of heat absorbed by the system in two cases, and $$\Delta$$UA and $$\Delta$$UB are changes in internal energies, respectively, then :
A
$$\Delta$$QA > $$\Delta$$QB ; $$\Delta$$UA > $$\Delta$$UB
B
$$\Delta$$QA < $$\Delta$$QB ; $$\Delta$$UA < $$\Delta$$UB
C
$$\Delta$$QA > $$\Delta$$QB ; $$\Delta$$UA = $$\Delta$$UB
D
$$\Delta$$QA = $$\Delta$$QB ; $$\Delta$$UA = $$\Delta$$UB
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