$A$ 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 half-life for radioactive decay of $^{14}C$ is $5730$ years. An archaeological artifact containing wood had only $80 \%$ of the $^{14}C$ found in a living tree. Estimate the age of the sample.

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

An organic compound undergoes first order decomposition. The time taken for its decomposition to $\frac{1}{8}$ and $\frac{1}{10}$ of its initial concentration are $t_{1/8}$ and $t_{1/10}$ respectively. What is the value of $\frac{t_{1/8}}{t_{1/10}}$? $[\log 2 = 0.30]$

The decomposition of $O_{3(g)}$ follows first order kinetics and is given by $O_{3(g)} \longrightarrow O_{2(g)} + O_{(g)}$. The rate constant for this reaction is $1.0 \times 10^{-3} \ s^{-1}$. The initial pressure of $O_{3(g)}$ is $100 \ atm$. What will be the partial pressure (in $atm$) of $O_3, O_2, O$ respectively after $38.38 \ minutes$?

The rate constant $k$,for the reaction ${N_2}{O_5}_{(g)} \to 2N{O_2}_{(g)} + \frac{1}{2}{O_2}_{(g)}$ is $2.3 \times 10^{-2} \ s^{-1}$. Which equation given below describes the change of $[{N_2}{O_5}]$ with time? $[{N_2}{O_5}]_0$ and $[{N_2}{O_5}]_t$ correspond to concentration of ${N_2}{O_5}$ initially and at time $t$.