The activation energy of a reaction can be determined from the slope of which of the following graphs?

For the reaction $A + B \rightarrow C + D$,$\Delta H = -20 \ kJ \ mol^{-1}$. The activation energy for the forward reaction is $85 \ kJ \ mol^{-1}$. The activation energy for the reverse reaction is ......... $kJ \ mol^{-1}$.

For a reaction taking place in three steps at the same temperature,the overall rate constant is $K = \frac{K_1 K_2}{K_3}$. If $E_{a1}$,$E_{a2}$,and $E_{a3}$ are $40 \ kJ/mol$,$50 \ kJ/mol$,and $60 \ kJ/mol$ respectively,the overall activation energy $E_a$ is . . . . . . $kJ/mol$.

Assertion $(A)$ : $A$ catalyst increases the rate of a reaction.
Reason $(R)$ : In presence of a catalyst, the activation energy of the reaction increases.
The correct answer is

In the Arrhenius equation,the fraction of molecules having energy equal to or greater than the activation energy at a given temperature is represented by .....

For a reaction,the value of rate constant at $300 \ K$ is $6.0 \times 10^5 \ s^{-1}$. The value of Arrhenius factor $A$ at infinitely high temperature is