The first order rate constant for the decomposition of $N_2O_5$ is $6.2 \times 10^{-4} \ s^{-1}$. The half-life period for this decomposition in seconds is:

If $50\%$ of a reaction occurs in $100 \ s$ and $75\%$ of the reaction occurs in $200 \ s$,the order of this reaction is

$A ( g ) \rightarrow 2 B ( g ) + C ( g )$ is a first order reaction. The initial pressure of the system was found to be $800 \ mm \ Hg$ which increased to $1600 \ mm \ Hg$ after $10 \ min$. The total pressure of the system after $30 \ min$ will be . . . . . . $mm \ Hg$. (Nearest integer)

For the first order reaction,half life is $14 \, sec$. The time required for the initial concentration to reduce to $\frac{1}{8}$ of its value is .......... $sec$.

The time of completion of $90\%$ of a first order reaction is approximately

What is the time required for $75 \%$ completion of a first order reaction if the rate constant is $23.03 \text{ minute}^{-1}$ (in $\text{ s}$)?