The minimum energy required for molecules to participate in a chemical reaction is called $.......$.

The activation energy of a reaction is $0$. The rate constant of the reaction:

The rate constant,$k$ for a first order reaction,$C_2H_5I_{(g)} \rightarrow C_2H_{4(g)} + HI_{(g)}$ is $x \ s^{-1}$ at $600 \ K$ and $4x \ s^{-1}$ at $700 \ K$. The energy of activation of the reaction (in $kJ \ mol^{-1}$) is (in $.16$)

The reaction: $Cr_{2}O_{3} + 2 Al \rightarrow Al_{2}O_{3} + 2 Cr$ $\quad (\Delta_{r}G^{\Theta} = -421 \ kJ)$ is thermodynamically feasible as is apparent from the Gibbs energy value. Why does it not take place at room temperature?

Fill in the blank :
$1.$ In collision theory the molecules are hard .........
$2.$ In a reality the molecules are hard ..........
$3.$ Collision take place with .......... species.

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