# NEET Chemistry Chemical Kinetics Questions Solved

The half-life for radioactive decay of ${}^{14}C$ is 5730 y. An archaeological artefact contained wood had only 80% of the ${}^{14}C$ found in a living tree. Estimate the age of the sample. [Radioactive decays follow the first order kinetics]

(A) 1657.3 y

(B) 1845.4 y

(C) 1512.4 y

(D) 1413.1 y

(B)

If a is the initial ${}^{14}C$ activity in a living tree, then

Therefore, $t=\frac{2.303}{0.693/{t}_{1/2}}\mathrm{log}\frac{a}{\frac{80}{100}a}$
$=\frac{2.303×5730y}{0.693}\mathrm{log}\frac{100}{80}$