The minimum energy necessary to permit a reaction is

Activation energy of a reaction is

$A$ reaction takes place in three steps with individual rate constant and activation energy as follows:

$Step$	$Rate \ constant$	$Activation \ energy$
$Step-1$	$k_1$	$E_{a1} = 180 \ kJ/mol$
$Step-2$	$k_2$	$E_{a2} = 80 \ kJ/mol$
$Step-3$	$k_3$	$E_{a3} = 50 \ kJ/mol$

If overall rate constant,$k = (\frac{k_1 k_2}{k_3})^{2/3}$,then overall activation energy of the reaction will be .......... $kJ/mol$.

Which of the following statements is true about the equilibrium constant and rate constant of a single-step chemical reaction?

An endothermic reaction $A \to B$ has an activation energy of $15 \ kcal/mol$ and an enthalpy change of reaction of $5 \ kcal/mol$. The activation energy of the reverse reaction $B \to A$ is ......... $kcal/mol$.

Reactant $A$ converts to product $D$ through the given mechanism (with the net evolution of heat) :

$A \rightarrow B$	$slow ; \Delta H=+ve$
$B \rightarrow C$	$fast ; \Delta H=-ve$
$C \rightarrow D$	$fast ; \Delta H=-ve$

Which of the following represents the above reaction mechanism ?