$\mathrm{A}\to \mathrm{B},∆\mathrm{H}=-10J {\mathrm{mol}}^{-1}$ Ea(f) = 50 J mol^-1

Then Ea(b) B$\to$A in k j mol^-1 will be?

$$\begin{gathered} ∆\mathrm{H}=-10J {\mathrm{mol}}^{-1} \\ \mathrm{It} \mathrm{is} \mathrm{an} \mathrm{exothermic} \mathrm{reaction} \\ \mathrm{Ea}\left(\mathrm{b}\right) = \mathrm{Ea}\left(\mathrm{f}\right) - ∆\mathrm{H} = 50 - (-10) = 60 J {\mathrm{mol}}^{-1} \\ = 0.06 k \mathrm{J} {\mathrm{mol}}^{-1} \end{gathered}$$