Half-life for a first order reaction is $6.93 \ hour$. What is the time required for $80 \%$ completion of the reaction (in $hours$)?

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)

Calculate the rate constant of the first order reaction if $20 \%$ of the reactant decomposes in $15 \ minutes$.

In the reaction $2N_2O_5 \to 4NO_2 + O_2$,the initial pressure is $500 \ atm$ and the rate constant $K$ is $3.38 \times 10^{-5} \ s^{-1}$. After $10 \ minutes$,the final pressure of $N_2O_5$ is ........ $atm$.

Dissociation of $N_2O_5$ dissolved in $CCl_4$ at constant temperature: $N_2O_{5(soln)} \to 2NO_{2(soln)} + \frac{1}{2}O_{2(g)}$. This is a first order reaction. The velocity constant is $5.0 \times 10^{-4} \ s^{-1}$. The initial concentration of $N_2O_5$ is $0.25 \ mol \ L^{-1}$. How much time is required to produce $0.20 \ mol \ L^{-1}$ concentration of $NO_2$ (in $s$)?

For a first-order reaction, if the initial concentration $[A]_0 = 1.0 \text{ M}$ and the concentration after time $t = 276 \text{ s}$ is $[A]_t = 0.25 \text{ M}$, find the value of the rate constant $(k)$. (in $\text{ s}^{-1}$)