The number of molecules with energy greater than the threshold energy for a reaction increases five fold by a rise of temperature from 27°Cand 42°C .It s energy of activation in J/mol is____
$\left(\text{ Take }\ln 5=1.6094,\mathrm{R}=8.314\mathrm{J}{\mathrm{mol}}^{-1}{\mathrm{K}}^{-1}\right)$