1
JEE Main 2021 (Online) 17th March Morning Shift
+4
-1
Two ideal polyatomic gases at temperatures T1 and T2 are mixed so that there is no loss of energy. If F1 and F2, m1 and m2, n1 and n2 be the degrees of freedom, masses, number of molecules of the first and second gas respectively, the temperature of mixture of these two gases is :
A
$${{{n_1}{F_1}{T_1} + {n_2}{F_2}{T_2}} \over {{F_1} + {F_2}}}$$
B
$${{{n_1}{F_1}{T_1} + {n_2}{F_2}{T_2}} \over {{n_1}{F_1} + {n_2}{F_2}}}$$
C
$${{{n_1}{T_1} + {n_2}{T_2}} \over {{n_1} + {n_2}}}$$
D
$${{{n_1}{F_1}{T_1} + {n_2}{F_2}{T_2}} \over {{n_1} + {n_2}}}$$
2
JEE Main 2021 (Online) 17th March Morning Shift
+4
-1
Two identical metal wires of thermal conductivities K1 and K2 respectively are connected in series. The effective thermal conductivity of the combination is :
A
$${{2{K_1}{K_2}} \over {{K_1} + {K_2}}}$$
B
$${{{K_1} + {K_2}} \over {{K_1}{K_2}}}$$
C
$${{{K_1} + {K_2}} \over {2{K_1}{K_2}}}$$
D
$${{{K_1}{K_2}} \over {{K_1} + {K_2}}}$$
3
JEE Main 2021 (Online) 17th March Morning Shift
+4
-1
Out of Syllabus
A Carnot's engine working between 400 K and 800 K has a work output of 1200 J per cycle. The amount of heat energy supplied to the engine from the source in each cycle is :
A
2400 J
B
1600 J
C
1800 J
D
3200 J
4
JEE Main 2021 (Online) 16th March Evening Shift
+4
-1
Calculate the value of mean free path ($$\lambda$$) for oxygen molecules at temperature 27$$^\circ$$C and pressure 1.01 $$\times$$ 105 Pa. Assume the molecular diameter 0.3 nm and the gas is ideal. (k = 1.38 $$\times$$ 10$$-$$23 JK$$-$$1)
A
32 nm
B
58 nm
C
86 nm
D
102 nm
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