The standard free energy of activation of a reaction $A$ is $90 \mathrm{~kJ} \mathrm{~mol}^{-1}\left(21.5 \mathrm{kcal} \mathrm{mol}^{-1}\right)$ at $298 \mathrm{~K}$. Reaction $B$ is one million times faster than reaction $A$ at the same temperature. The products of each reaction are $10 \mathrm{~kJ} \mathrm{~mol}^{-1}\left(2.4 \mathrm{kcal} \mathrm{mol}^{-1}\right)$ more stable than the reactants.
(a) What is the standard free energy of activation of reaction $B$ ?
(b) Draw reaction free-energy diagrams for the two reactions showing the two values of $\Delta G^{\circ}$ to scale.
(c) What is the standard free energy of activation of the reverse reaction in each case?