Activation energy is defined as:

If the activation energy of a reaction is $80.9 \, kJ \, mol^{-1}$,the fraction of molecules at $700 \, K$,having enough energy to react to form products is $e^{-x}$. The value of $x$ is ....... . (Rounded off to the nearest integer) $[$Use $R = 8.31 \, J \, K^{-1} \, mol^{-1}]$

What is the activation energy for the reverse of this reaction?
$N_2O_{4(g)} \to 2NO_{2(g)}$
Data for the given reaction is:
$\Delta H = +54 \ kJ$ and $E_a = +57.2 \ kJ$
Answer in $kJ$.

Consider a complex reaction taking place in three steps with rate constants $k_1$,$k_2$,and $k_3$ respectively. The overall rate constant $k$ is given by the expression $k = \sqrt{\frac{k_1 k_3}{k_2}}$. If the activation energies of the three steps are $60$,$30$,and $10 \ kJ \ mol^{-1}$ respectively,then the overall energy of activation in $kJ \ mol^{-1}$ is $..........$ $(Nearest \ integer)$

The activation energy of a reaction is zero. Its rate constant at $280 \ K$ is $1.6 \times 10^{-6} \ s^{-1}$,the rate constant at $300 \ K$ is

For a reaction,the graph of $\ln k$ (on y-axis) and $1 / T$ (on x-axis) is a straight line with a slope $-2 \times 10^4 \ K$. The activation energy of the reaction (in $kJ \ mol^{-1}$) is $(R = 8.3 \ J \ K^{-1} \ mol^{-1})$