Chemical Kinetics And Nuclear Chemistry

Consider the two different first order reactions given below

$$\begin{aligned} & \mathrm{A}+\mathrm{B} \rightarrow \mathrm{C} \text { (Reaction 1) } \\ & \mathrm{P} \rightarrow \mathrm{Q} \text { (Reaction 2) } \end{aligned}$$

The ratio of the half life of Reaction 1 : Reaction 2 is \(5: 2\) If \(t_1\) and \(t_2\) represent the time taken to complete \(2 / 3^{\text {rd }}\) and \(4 / 5^{\text {th }}\) of Reaction 1 and Reaction 2 , respectively, then the value of the ratio \(t_1: t_2\) is _________ \(\times 10^{-1}\) (nearest integer).
[Given : \(\log _{10}(3)=0.477\) and \(\log _{10}(5)=0.699\)]