1
JEE Main 2021 (Online) 27th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
Two Carnot engines A and B operate in series such that engine A absorbs heat at T1 and rejects heat to a sink at temperature T. Engine B absorbs half of the heat rejected by Engine A and rejects heat to the sink at T3. When workdone in both the cases is equal, to value of T is :
A
$${2 \over 3}{T_1} + {3 \over 2}{T_3}$$
B
$${1 \over 3}{T_1} + {2 \over 3}{T_3}$$
C
$${3 \over 2}{T_1} + {1 \over 3}{T_3}$$
D
$${2 \over 3}{T_1} + {1 \over 3}{T_3}$$
2
JEE Main 2021 (Online) 27th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
The number of molecules in one litre of an ideal gas at 300 K and 2 atmospheric pressure with mean kinetic energy 2 $$\times$$ 10$$-$$9 J per molecules is :
A
0.75 $$\times$$ 1011
B
3 $$\times$$ 1011
C
1.5 $$\times$$ 1011
D
6 $$\times$$ 1011
3
JEE Main 2021 (Online) 27th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
In the reported figure, there is a cyclic process ABCDA on a sample of 1 mol of a diatomic gas. The temperature of the gas during the process A $$\to$$ B and C $$\to$$ D are T1 and T2 (T1 > T2) respectively.

JEE Main 2021 (Online) 27th July Morning Shift Physics - Heat and Thermodynamics Question 136 English
Choose the correct option out of the following for work done if processes BC and DA are adiabatic.
A
WAB = WDC
B
WAD = WBC
C
WBC + WDA > 0
D
WAB < WCD
4
JEE Main 2021 (Online) 27th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
A body takes 4 min. to cool from 61$$^\circ$$ C to 59$$^\circ$$ C. If the temperature of the surroundings is 30$$^\circ$$ C, the time taken by the body to cool from 51$$^\circ$$ C to 49$$^\circ$$ C is :
A
4 min.
B
3 min.
C
8 min.
D
6 min.
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