$A$ reaction is $50\%$ complete in $2 \ hours$ and $75\%$ complete in $4 \ hours$. The order of reaction is

$A$ first order reaction is found to have a rate constant,$k = 5.5 \times 10^{-14} \ s^{-1}$. Find the half-life of the reaction.

What is the half-life of a first-order reaction if the time required to decrease the concentration of the reactant from $0.8 \text{ M}$ to $0.2 \text{ M}$ is $12 \text{ hours}$ (in $\text{ hours}$)?

Show that in a first order reaction,the time required for completion of $99.9 \%$ is $10$ times the half-life $(t_{1/2})$ of the reaction.

The rate constant of a first order reaction is $3 \times 10^{-6} \ s^{-1}$. If the initial concentration is $0.10 \ M$,the initial rate of reaction is:

For a first-order reaction,the ratio of the time required for $99.9\%$ completion to the time required for $50\%$ completion is: