For a first order reaction,

Options

A. The degree of dissociation is equal to `(1-e^(-kt))`.
B. A plot of reciprocal concentration of the reactant versus time gives a straight line.
C. The time taken for the completion of `75%` of the reaction is theice the time taken for `1//2` of the reaction.
D. The pre-exponential factor in the Arrhenius equation has the dimenison of time `T^(-1)`.

Answer

A, D

Explanation

`k = (2.303)/(t) log.(A_(0))/(A)`
or `kt = ln.(A_(0))/(A) = ln.(1)/(1-a)`
If `a` is the degree of dissociation,
`e^(kt) = (1)/(1-a)`
or `1-a = e^(-kt)`
or `a = 1-e^(-kt)`
`:. k = Ae^(-E_(a)//RT)` (Arrhenius equation)
Pre-exponential factor has the same dimenisons as rate constant, and for a first ordr reaction that is `(t^(-1))`