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

$A$ first order reaction has a rate constant $1.15 \times 10^{-3} \, s^{-1}$. How long will $5 \, g$ of this reactant take to reduce to $3 \, g$?

Initial concentration of reactant in a first order reaction is $0.08 \text{ mol dm}^{-3}$. What concentration would remain after $40 \text{ minutes}$? (Given $\frac{[A]_0}{[A]_t} = 5.00$)

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.

The following data is obtained during the first-order thermal decomposition of $2A_{(g)} \longrightarrow B_{(g)} + C_{(s)}$ at constant volume and temperature. The rate constant in $min^{-1}$ is:

$S$.No.	Time	Total pressure in $Pa$
$1$.	At $t = 10 \ min$	$300$
$2$.	At $t = \infty$	$200$

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