JEE PYQ: Chemical Kinetics Question 41
Question 41 - 2019 (12 Jan Shift 2)
Decomposition of X exhibits a rate constant of 0.05 $\mu$g/year. How many years are required for the decomposition of 5 $\mu$g of X into 2.5 $\mu$g?
(1) 50
(2) 25
(3) 20
(4) 40
Show Answer
Answer: (1)
Solution
Rate constant of decomposition of $X = 0.05$ $\mu$g/year. Unit of rate constant confirms that the decomposition of $X$ is a zero order reaction. For zero order kinetics: $[\text{X}] = [\text{X}]_0 - kt$. $kt = [\text{X}]_0 - [\text{X}]$. $t = \frac{[\text{X}]_0 - [\text{X}]}{k} = \frac{5 - 2.5}{0.05} = \frac{2.5}{0.05} = 50$ years.
BETA
