The relation between the rate constant and temperature according to the Arrhenius equation is:

Activation energy for the hydrolysis of sucrose by acid is $X \ kJ \ mol^{-1}$ whereas activation energy for the hydrolysis of sucrose by sucrase is $Y \ kJ \ mol^{-1}$. $X$ and $Y$ respectively are

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.

For a first order reaction $(A \rightarrow B)$,the temperature $(T)$ dependent rate constant $(k)$ in $s^{-1}$ was found to follow the equation: $\log k = \left(-\frac{20}{T}\right)+4$. The activation energy $(E_a)$ and pre-exponential factor $(A)$ respectively,are

For the reaction,$A \rightleftharpoons B$,$E_a = 50 \ kJ \ mol^{-1}$ and $\Delta H = -20 \ kJ \ mol^{-1}$. When a catalyst is added,$E_a$ decreases by $10 \ kJ \ mol^{-1}$. What is the $E_a$ for the backward reaction in the presence of the catalyst?

$A$ large increase in the rate of reaction for a small increase in temperature is due to: