Based on the provided energy profile diagram,how many steps are in the mechanism of the reaction?

For $N_2 + 3H_2 \rightarrow 2NH_3$,$\Delta H = -22 \ kcal$,and $E_a = 70 \ kcal$. Hence $E_a$ for $2NH_3 \rightarrow N_2 + 3H_2$ is $.....$ $kcal$.

Explain the collision theory of chemical reactions.

The rate of a chemical reaction doubles for every $10^\circ \text{C}$ rise in temperature. If the temperature is increased by $50^\circ \text{C}$,the rate of reaction will increase by a factor of ........

Rate constant of a reaction is given as $\log_{10} K = -\frac{2000}{T} + 6.0$. Activation energy is ....... $kcal$.

The activation energy of a reaction is......