Two moles of an ideal gas with (CP)/(CV) = 5/3 are mixed with 3 moles of another ideal gas with (CP)/(CV) = 4/3. The value of (CP)/(CV) for the mixture is: (a) 1.50 (b) 1.45 (c) 1.47 (d) 1.42

Answer: (d). CV = (R)/(γ - 1): gas 1 CV = 3/2R, gas 2 CV = 3R. CVmix = (2(1.5R) + 3(3R))/(5) = 12R/5 = 2.4R CPmix = 3.4R, γ = (3.4)/(2.4) ≈ 1.42 So the answer is (d) 1.42.

Two moles of an ideal gas with (CP)/(CV) = 5/3 are mixed with 3 moles… | JEE Main 2020 (7 Jan, Shift 1)

Q48JEE Main 2020 · 7 JAN · SHIFT 1Medium

Specific Heats of Gases - Cp, Cv, γ & Mayer's Relation

Two moles of an ideal gas with $\frac{C_P}{C_V} = \frac{5}{3}$ are mixed with 3 moles of another ideal gas with $\frac{C_P}{C_V} = \frac{4}{3}$ . The value of $\frac{C_P}{C_V}$ for the mixture is:

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Answer: (d)

$C_V = \dfrac{R}{\gamma - 1}$ : gas 1 $C_V = \dfrac{3}{2}R$ , gas 2 $C_V = 3R$ .
$C_V^{mix} = \dfrac{2(1.5R) + 3(3R)}{5} = \dfrac{12R}{5} = 2.4R$
$C_P^{mix} = 3.4R$ , $\gamma = \dfrac{3.4}{2.4} \approx 1.42$
So the answer is (d) 1.42.

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Specific Heats of Gases - Cp, Cv, γ & Mayer's Relation question from JEE Main 2020 (7 Jan, Shift 1)

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