The half-life of a first-order reaction is $2000$ years. If the concentration after $8000$ years is $0.02 \, M$,then the initial concentration was $........... \, M$.

The following data were obtained during the first order thermal decomposition of a gas $A$ at constant volume:
$A_{(g)} \rightarrow 2 B_{(g)} + C_{(g)}$

$S.No.$	$Time/s$	$Total Pressure/(atm)$
$1.$	$0$	$0.1$
$2.$	$115$	$0.28$

The rate constant of the reaction is . . . . . . $\times 10^{-2} \ s^{-1}$ (nearest integer).

Consider the first-order gas-phase decomposition reaction given below:
$A_{(g)} \longrightarrow B_{(g)} + C_{(g)}$
The initial pressure of the system before the decomposition of $A$ was $P_i$. After time $t$,the total pressure of the system increased by $x \ units$ and became $P_t$. The rate constant $k$ for the reaction is given as:

$t_{1/4}$ for a first-order reaction is given as:

When the value of rate constant $(k)$ is $2.0 \text{ min}^{-1}$,then what will be the half-life of the reaction $(t_{1/2})$ in seconds?

Derive the half-life $t_{1/2}$ of a first-order reaction.