For a second$-$order elementary gas$-$phase reaction, the rate constant was experimentally found to be $3\mathrm{.}95{10}^{-4}Lmo{l}^{-1}{s}^{-1}$ at $50C$ and $3\mathrm{.}10{10}^{-2}Lmo{l}^{-1}{s}^{-1}$ at $85C.$ Calculate, at $50C,$ the activation energy $E_a,$ the pre$-$exponential factor $A,$ the enthalpy of activation $H^o,$ the Gibbs energy of activation $G^o$ and the entropy of activation $S^{?}0.$