Question

5 mg radioactive sample 90% disintegrate in 3 years then 99% disintegrate will be in

Answer 1

99% disintegrate will be in 6 years

Explanation:

All the radioactive decay generally follows first order kinetics decay.

Using integrated rate law for first order kinetics as:

$[A_t]=[A_0]e^{-kt}$

Where,  

$[A_t]$ is the concentration at time t

$[A_0]$ is the initial concentration

Given:

90 % is decomposed which means that 0.9 of $[A_0]$ is decomposed. So,

$\frac {[A_t]}{[A_0]}$ = 1 - 0.9 = 0.1

t = 3 years

$\frac {[A_t]}{[A_0]}=e^{-k\times t}$

$0.1=e^{-k\times 3}$

k = 0.7675 year⁻¹

Also,  

Given:

99 % is decomposed which means that 0.99 of $[A_0]$ is decomposed. So,

$\frac {[A_t]}{[A_0]}$ = 1 - 0.99 = 0.01

t = ?

$\frac {[A_t]}{[A_0]}=e^{-k\times t}$

$0.01=e^{-0.7675\times t}$

t = 6 years.

Learn more:-

https://brainly.in/question/8302615

https://brainly.in/question/7323265

#learnwithbrainly