$A$ first-order reaction takes $10 \ hours$ to complete $90\%$ of the reaction. How much time will it take to complete $99.9\%$ of the reaction (in $hours$)?

In the following graphs,which graph$(s)$ belong to a first-order reaction?

If the concentration unit decreases by a factor of $n$,what will be the value of the rate constant for a first-order reaction?

$t_{1/4}$ can be taken as the time taken for the concentration of a reactant to drop to $3/4$ of its initial value. If the rate constant for a first order reaction is $K$,the $t_{1/4}$ can be written as (in $/K$)

In a first order reaction,the concentration of reactant decreases from $800 \ mol/dm^3$ to $50 \ mol/dm^3$ in $2 \times 10^2 \ s$. The rate constant of the reaction in $s^{-1}$ is:

For a first-order reaction, $20 \text{ mmol}$ of reactant is reduced to $10 \text{ mmol}$ in $1.151 \text{ min}$. Find the rate constant $k$. (in $\text{ min}^{-1}$)