$A$ first order reaction has a specific reaction rate of $10^{-2} \ sec^{-1}.$ How much time will it take for $20 \ g$ of the reactant to reduce to $5 \ g?$ ........ $sec$

The rate constant of a first order reaction is $15 \times 10^{-3} \ s^{-1}$. How many seconds will $5.0 \ g$ of this reactant take to reduce to $3.0 \ g$?

In a first-order reaction,the concentration of reactant $X$ decreases from $0.1 \, M$ to $0.005 \, M$ in $40 \, min$. What will be the rate of reaction when the concentration of $X$ is $0.01 \, M$?

At $T(K)$,if the rate constant of a first order reaction is $4.606 \times 10^{-3} \ s^{-1}$,the time to reduce the initial concentration of the reactant to $1/10$ of its initial value in seconds is:

For a $1^{st}$ order reaction $R \rightarrow P$, the concentration of reactant $R$ changes from $0.1 \text{ M}$ to $0.025 \text{ M}$ in $40 \text{ minutes}$. The rate of reaction when the concentration of $R$ is $0.01 \text{ M}$ is

$A$ first-order reaction is $50\%$ complete in $45 \text{ minutes}$. How many hours will it take for the reaction to be $99.9\%$ complete?