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Two moles of helium are mixed with n with moles of hydrogen. If C_P/C_V = 3/2 for the mixture, then the value of n is -

1. 3/2
2. 2
3. 1
4. 3

Correct answer: 2

Solution

The ratio of specific heats, C_P/C_V, for an ideal gas mixture can be calculated using the contributions from each gas. Given that helium is monatomic and hydrogen is diatomic, the specific heat ratio for the mixture being 3/2 indicates that the proportion of hydrogen must be such that it balances the contributions from the two moles of helium, leading to n being equal to 2.

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