• # question_answer In Arrhenius equation for activation energy, $k=A{{e}^{-{{E}_{a}}/Rt}},$ A represents the following [a] Pre exponential factor [b] Frequency factor      [c]  Arrhenius factor         [d] Collision factor and frequency The correct answer is A)  $1$and $3$         B)  $1$ and $2$ C)  $3$ and $4$         D)  $-2$ and $3$

In Arrhenius equation, A is pre-exponential factor. Its units are identical to those of the units of rate constant. For first order reaction, its unit is ${{s}^{-1}},$ hence it is often called frequency factor. Note: It is sometimes also called Arrhenius factor.