question_answer

5. One mole of ideal monatomic gas\[(\gamma =5/3)\]is mixed with one mole of diatomic gas\[(\gamma =7/5)\]What is\[\gamma \]for the mixture? y denotes the ratio of specific heat at constant pressure, to that at constant volume                           [AIEEE 2004]

A)  3/2    

B)       23/15

C)  35/23              

D)       4/3

Correct Answer: A

Solution :

   

[a] Mayor's formula is

and

Therefore, using above two relations, we find

For monoatomic gas;

For diatomic gas;

When these two moles are mixed, then heat required to raise the temperature tois

Hence, for one mole, heat required

Alternate Solution

As,

Here,

Hence,