The rate constant of a reaction at  $500K$  and  $700K$  are   $0.02s^{-1}$  and  $0.2s^{-1}$  respectively. The activation energy of the reaction (in kj  $mo{l}^{-1}$ ) is   $\left(R=8.3J{k}^{-1}mo{l}^{-1}\right)$