A vessel contains 1 mole of O2 and 1 mole of He. The value of γ(gamma) for the mixture is?HOW? Pleassee explain

Thank u JAYANT for the formula. It helped me a lot. But the answer I got is 1.5.

But once again THANKS A LOT

LET

n1= no. moles of oxygen.=1 mole

n2=no. of moles of helium = 1 moles

Q is the total heat of mixture, Q1 is heat of pure oxygen, Q2 is heat of pure he mixture.

hence by conservation of energy,

Q = Q1 + Q2

(n1+ n2)Cp.dt = n1Cp1.dt + n2Cp2.dt

2.Cp = Cp1 + Cp2

       =7/2 R + 5/2R

        = 6R                        

Cp = 3R

Cv= 3R-R=2R

gamma= 3/2=1.5

Use the formula:

{N(oxygen)+N(helium)}/{γ(mixture)-1}=N(oxygen)/{γ(oxygen)-1}+N(helium)/{γ(helium)-1}

where,

N(oxygen) and N(helium) are given

and,

γ(oxygen)=gamma of diatomic gas(7/2)

γ(helium)=gamma of monoatomic gas(5/3)

ans=3/2