Give an example of a collision in the proper direction that results in the formation of a product.

$A$ given sample of milk turns sour at room temperature $(27^{\circ} C)$ in $5 \ h$. In a refrigerator at $-3^{\circ} C$,it can be stored $10$ times longer. The energy of activation for the souring of milk is

For a particular reaction,the rate constant becomes double on increasing temperature from $27^{\circ} C$ to $37^{\circ} C$. Calculate the approximate activation energy (in $kcal \ mol^{-1}$,$R=2 \ cal \ mol^{-1} \ K^{-1}$).

For reaction $A \to B$,the rate constant $k_1 = A_1 e^{-E_{a_1} / (RT)}$ and for the reaction $X \to Y$ the rate constant $k_2 = A_2 e^{-E_{a_2} / (RT)}$. If $A_1 = 10^8$,$A_2 = 10^{10}$ and $E_{a_1} = 600 \ cal/mol$,$E_{a_2} = 1800 \ cal/mol$,then the temperature at which $k_1 = k_2$ is (Given : $R = 2 \ cal/K \cdot mol$)

In the Arrhenius equation,the rate of reaction is given by $k = A{e^{ - {E_a}/RT}}$. What does $E_a$ represent?

Activation energy of a reaction is