${\text{t}}_{\text{1/4}}$can be taken as the time taken for the concentration of a reactant to drop to $\frac{3}{4}$of its initial         value. If the rate constant for a first order reaction is K, the ${\text{t}}_{\text{1/4}}$ of its initial value. If the rate constant for a first order reaction is K, the ${\text{t}}_{\text{1/4}}$ can be written as