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 $3.0 \ g$?

The reaction $X \rightarrow$ products is a first-order reaction. If the concentration of reactant $X$ decreases from $0.1 \, M$ to $0.025 \, M$ in $40 \, \text{minutes}$,what will be the rate of the reaction when the concentration of the reactant is $0.01 \, M$?

The half-life of a first-order reaction is $1 \text{ hour}$. What fraction of the reactant will remain after $3 \text{ hours}$?

$N_2O_5$ decomposes to $NO_2$ and $O_2$ and follows first order kinetics. After $50 \, min$,the pressure inside the vessel increases from $50 \, mm \, Hg$ to $87.5 \, mm \, Hg$. The pressure of the gaseous mixture after $100 \, min$ at constant temperature will be ........... $mm \, Hg$

For the first-order reaction $N_2O_5 \text{ (in } CCl_4) \rightarrow 2NO_2 + \frac{1}{2}O_{2(g)}$,the rate constant is $6.2 \times 10^{-4} \, s^{-1}$. What will be the rate of reaction when $[N_2O_5] = 1.25 \, mol \, L^{-1}$?

What is the time required for completion of $90 \%$ of a first order reaction?