Nuclear Chemistry Ques 10
10. The radioactive isotope, tritium, $( _1^{3} H)$ has a halflife of $12.3$ years. If the initial amount of tritium is $32$ $ mg$, how many milligrams of it would remain after $49.2$ years?
[2003]
(a) $8$ $ mg$
(b) $1$ $ mg$
(c) $2$ $ mg$
(d) $4$ $ mg$
Show Answer
Answer:
Correct Answer: 10.(c)
Solution:
- (c) Given $t _{1 / 2}=12.3$ years
Initial amount $(N_0)=32$ $ mg$
Total time $=49.2$ years
No. of half lives $(n)=\frac{T}{t _{1 / 2}}=\frac{49.2}{12.3}=4$
Now $N_t=N_0(\frac{1}{2})^{n}=32(\frac{1}{2})^{4}=\frac{32}{16}=2 $ $mg$
Hence $32 $ $mg$ becomes $2$ $ mg$ in $49.2$ years
BETA
