The correct options are
A The pre-exponential factor becomes equal to the rate constant of the reaction at extremely high temperature.
B When the activation energy of the reaction is zero, the rate becomes independent of temperature.
C The term
e−Ea/RT represents the fraction of the molecules having energy in excess of threshold value.
The Arrhenius equation describes the effect of temperature on the velocity of a chemical reaction, the basis of all predictive expressions used for calculating reaction-rate constants. In the Arrhenius equation, k is the reaction rate constant, A and E are numerical constants characteristic of the reacting substances, R is the thermodynamic gas constant, and T is the absolute temperature.
Arhenius equation is k=Ae−Ea/RT
So when T→∞;k=A the rate constant becomes equal to frequency factor.
When the activation energy of the reaction is zero, k=A, the rate becomes independent of temperature.
Larger the activation energy of a reaction, smaller is the value of rate constant.
Larger the activation energy of a reaction, greater is the influence of change in temperature on rate constant.
For lower temperature range, increase in temperature causes more change in the value of k than the same increase in temperature for high temperature range.