# NEET Physics Thermodynamics Questions Solved

An insulator container contains 4 moles of an ideal diatomic gas at temperature T. Heat Q is supplied to this gas, due to which 2 moles of the gas are dissociated into atoms but temperature of the gas remains constant. Then

(1) Q = 2RT

(2) Q = RT

(3) Q = 3RT

(4) Q = 4RT

(2) Q = ΔU = UfUi = [internal energy of 4 moles of a monoatomic gas + internal energy of 2 moles of a diatomic gas] – [internal energy of 4 moles of a diatomic gas]

$=\left(4×\frac{3}{2}RT+2×\frac{5}{2}RT\right)-\left(4×\frac{5}{2}RT\right)$= RT

= RT

Note : (1) 2 moles of diatomic gas becomes 4 moles of a monoatomic gas when gas dissociated into atoms.

(2) Internal energy of μ moles of an ideal gas of degrees of freedom F is given by $U=\frac{f}{2}\mu RT$

f = 3 for a monoatomic gas and 5 for diatomic gas.

Difficulty Level:

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