1
JEE Main 2021 (Online) 27th August Evening Shift
Numerical
+4
-1
A heat engine operates between a cold reservoir at temperature T2 = 400 K and a hot reservoir at temperature T1. It takes 300 J of heat from the hot reservoir and delivers 240 J of heat to the cold reservoir in a cycle. The minimum temperature of the hot reservoir has to be ______________ K.
2
JEE Main 2021 (Online) 27th August Morning Shift
Numerical
+4
-1
A rod CD of thermal resistance 10.0 KW$$-$$1 is joined at the middle of an identical rod AB as shown in figure. The end A, B and D are maintained at 200$$^\circ$$C, 100$$^\circ$$C and 125$$^\circ$$C respectively. The heat current in CD is P watt. The value of P is ................. .

3
JEE Main 2021 (Online) 25th July Evening Shift
Numerical
+4
-1
A system consists of two types of gas molecules A and B having same number density 2 $$\times$$ 1025/m3. The diameter of A and B are 10 $$\mathop A\limits^o$$ and 5 $$\mathop A\limits^o$$ respectively. They suffer collision at room temperature. The ratio of average distance covered by the molecule A to that of B between two successive collision is ____________ $$\times$$ 10$$-$$2
4
JEE Main 2021 (Online) 22th July Evening Shift
Numerical
+4
-1
In 5 minutes, a body cools from 75$$^\circ$$C to 65$$^\circ$$C at room temperature of 25$$^\circ$$C. The temperature of body at the end of next 5 minutes is _________$$^\circ$$ C.
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