Q9. Energy of 10 non rigid diatomic molecules at temperature $T$ is :\\ (1) $70 \mathrm {~K} _ { \mathrm { B } } \mathrm { T }$\\ (2) $35 \mathrm {~K} _ { \mathrm { B } } \mathrm { T }$\\ (3) $\frac { 7 } { 2 } \mathrm { RT }$\\ (4) 35 RT