Which graph shows zero activation energy?

For a reaction having three steps, the overall rate constant is $K = \frac{k_1 k_2}{k_3}$. The values of $E_{a1}$, $E_{a2}$ and $E_{a3}$ (activation energies for each step) are $40$, $50$ and $60 \text{ kJ mol}^{-1}$ respectively. The overall activation energy $E_a$ of the reaction is:

The rate constant for a first order reaction is given by the following equation:
$\ln k = 33.24 - \frac{2.0 \times 10^{4} \, K}{T}$
The activation energy for the reaction is given by $... \, kJ \, mol^{-1}$. (In nearest integer)
(Given: $R = 8.3 \, J \, K^{-1} \, mol^{-1}$)

For a reaction $A \rightarrow B$,the enthalpy of reaction is $-4.2 \ kJ \ mol^{-1}$ and the enthalpy of activation is $9.6 \ kJ \ mol^{-1}$. The correct potential energy profile for the reaction is shown in which option?

The first order rate constant $k$ is related to temperature $T$ as $\log \, k = 15.0 - (10^{6} / T)$. Which of the following pairs of values for the Arrhenius factor $A$ and activation energy $E_a$ is correct?

The rate constant of a reaction depends on ................