Question

For a first order reaction, more than one option are correct-

• A. The degree of dissociation is equal to $\left(1- e ^{- K t}\right)$
• B. The time taken for the completion of $75 \%$ reaction is thrice the $t_{1 / 2}$ of the reaction
• C. The pre-exponential factor in the Arrhenius equation has the dimension of time, $\left( T ^{-1}\right)$
• D. Both (a) & (c)

Answer 1

Answer: (D)

In option a, for first order reaction, if degree of dissociation is $\alpha,$ then
$k=\frac{2.303}{t} \log _{10} \frac{1}{1-\alpha}$

or $k t =\log _{e} \frac{1}{1-\alpha}=-\log _{e}(1-x)$

$e^{-k t}=1-\alpha$

$\alpha=1- e ^{- kt }$

in option,c according to Arrhenius equation

$k = A.e ^{- E _{ a } /Rt }$

A has $T^{(-1)}$ dimension