QJEEM18Ph7bdf: JEE Main 2018 Physics - Class 11 JEEM18Ph7bdf Solution: Two moles of helium are mixed with n moles of hydrogen. If C p…

Question

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Two moles of helium are mixed with n moles of hydrogen. If

\frac{C p}{C v} = \frac{3}{2}

for the mixture, then the value of n is :

Accepted Answer

\frac{C_{p}}{C_{v}} = \frac{f_{m i x} + 2}{f_{m i x}} = \frac{3}{2}

\Rightarrow

f_mix = 4

As, f_mix =

\frac{n_{1} f_{1} + n_{2} f_{2}}{n_{1} + n_{2}}

\Rightarrow

4 =

\frac{2 \times 3 + n \times 5}{2 + n}

\Rightarrow

n = 2 moles.

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