For the gaseous reaction $A(g) \longrightarrow B(g) + C(g) + D(g)$,starting with an initial pressure of $400 \ atm$. If the total pressure after $2 \ hr$ is $800 \ atm$,the value of the rate constant is: (consider the reaction to be $1^{st}$ order): (in $hr^{-1}$)

The time required for a first-order reaction to be $90\%$ complete is approximately .........

$99 \%$ of a first order reaction was completed in $64 \text{ min}$. In how many minutes will $99.9 \%$ of the reaction be complete?

In a first order decomposition reaction,the time taken for the decomposition of reactant to one fourth and one eighth of its initial concentration are $t_1$ and $t_2 \ s$,respectively. The ratio $t_1 / t_2$ will be:

What is the time needed to reduce the initial concentration of reactant to $10 \%$ in a first order reaction if its half life time is $10 \ minute$?

The rate constant $k$,for the reaction ${N_2}{O_5}_{(g)} \to 2N{O_2}_{(g)} + \frac{1}{2}{O_2}_{(g)}$ is $2.3 \times 10^{-2} \ s^{-1}$. Which equation given below describes the change of $[{N_2}{O_5}]$ with time? $[{N_2}{O_5}]_0$ and $[{N_2}{O_5}]_t$ correspond to concentration of ${N_2}{O_5}$ initially and at time $t$.