The half-life of a first-order reaction is $69.35 \, \text{sec}$. The value of the rate constant of the reaction is .......... $\sec^{-1}$.

Gaseous cyclobutene isomerizes to butadiene in a first order process which has a $k$ value of $3.3 \times 10^{-4} \ s^{-1}$ at $153^{\circ}C$. The time in minutes it takes for the isomerization to proceed $40\%$ to completion at this temperature is ..........
(Rounded off to the nearest integer)

$A$ flask contains a mixture of compounds $AB$ and $XY$. Both decompose by first-order kinetics upon heating. If the half-life periods of $AB$ and $XY$ are $30 \ min$ and $10 \ min$ respectively,how many minutes will it take for the concentration of $AB$ to be four times the concentration of $XY$? (Assume initial concentrations of $AB$ and $XY$ are equal.)

The half-life period of a $1^{st}$ order reaction is $60 \ minutes$. What percentage will be left over after $240 \ minutes$ (in $\%$)?

It takes $1 \, h$ for a first order reaction to go to $50 \, \%$ completion. The total time required for the same reaction to reach $87.5 \, \%$ completion will be $..... \, h$.

In a first order reaction,the concentration of the reactant decreases from $20 \ mmol$ to $10 \ mmol$ in $1.151 \ min$. What is the rate constant (in $min^{-1}$)?