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Question: Answered & Verified by Expert
The radiosotope tritium $\left({ }_1^3 \mathrm{H}\right)$ has a lalf life of 12.3 years. If the initial amount of tritium is $32 \mathrm{mg}$, how many milligrams of it would remain after 49.2 years
ChemistryChemical KineticsNEETNEET 2003
Options:
  • A $1 \mathrm{mg}$
  • B $2 \mathrm{mg}$
  • C $4 \mathrm{mg}$
  • D $8 \mathrm{mg}$
Solution:
2601 Upvotes Verified Answer
The correct answer is: $2 \mathrm{mg}$
$$
\begin{aligned}
\mathrm{T} & =\mathrm{t}^{1 / 2} \times n \\
n & =\frac{49.2}{12.3}=4 \\
\mathrm{~N} & =\mathrm{N}_0(1 / 2)^n \\
& =32(1 / 2)^4 \\
& =2 \mathrm{mg}
\end{aligned}
$$

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