JEE Main 2026 Apr 6 Shift 2, Physics Q10: Laws of Thermodynamics

JEE Main2026Apr 6, Shift 2Physics

If 2 mole of an ideal monoatomic gas at temperature $T$ is mixed with 6 mole of another ideal monoatomic gas at temperature $2 T$ then the temperature of mixture is:

A
$\frac{5}{2} T$
B
$\frac{5}{4} T$
C
$\frac{7}{2} T$
D
$\frac{7}{4} T$

Solution

For mixing at constant volume (no heat lost to surroundings), energy conservation gives:

$T_{mi x} = \frac{n _{1} C _{V} T _{1} + n _{2} C _{V} T _{2}}{( n _{1} + n _{2} ) C _{V}} = \frac{n _{1} T _{1} + n _{2} T _{2}}{n _{1} + n _{2}}$ (same $C_{V}$ cancels).

$T_{mi x} = \frac{2 T + 6 ( 2 T )}{2 + 6} = \frac{14 T}{8} = \frac{7 T}{4}$ .

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JEE Main 2026 Apr 6 Shift 2, Physics Q10: Laws of Thermodynamics

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