Degrees of freedom of \(He \left(f_{ He }\right)=3\)

Degrees of freedom of \(O _2\left(f_{ O _2}\right)=5\)

Degrees of freedom of \(O _3\left( f _{ O _3}\right)=6\)

\(n_{ He }=2, \quad n_{ O _2}=4 \quad n_{ O _3}=1\)

Energy of mixture = Sum of individual energies

\(=\left(n_{ He}f_{ He }+n_{ O _2} f_{ O _2}+n_{ O _3} f_{ O _3}\right) \frac{R T}{2}\)

\(=(2 \times 3+4 \times 5+1 \times 6) \frac{R T}{2}\)

\(=(3+10+3) R T\)

\(=16 R T\)