JEE PYQ: Chemical Kinetics Question 22
Question 22 - 2020 (07 Jan Shift 1)
During the nuclear explosion, one of the products is $^{90}\text{Sr}$ with half life of 6.93 years. If 1 $\mu$g of $^{90}\text{Sr}$ was absorbed in the bones of a newly born baby in place of Ca, how much time, in years, is required to reduce it by 90% if it is not lost metabolically ____
Show Answer
Answer: 23.03
Solution
$t_{1/2} = 6.93$ years, $a = 10^{-6}$ g. $K = \frac{0.693}{t_{1/2}} = \frac{0.693}{6.93} = 0.1$. For 1st order reaction: $t = \frac{2.303}{K}\log\frac{a}{a - x} = \frac{2.303}{0.1}\log\frac{10^{-6}}{10^{-7}} = \frac{2.303}{0.1} = 23.03$ years.
BETA
