Search any question & find its solution
Question:
Answered & Verified by Expert
The half life of a radium is about 1600 years. Of $100 \mathrm{~g}$ of radium existing now 25 g will remain unchanged after :-
Options:
Solution:
1311 Upvotes
Verified Answer
The correct answer is:
3200 years
Applying the formula
$$
\begin{aligned}
N & =N_0\left(\frac{1}{2}\right)^n \\
\Rightarrow \quad \frac{N}{N_0} & =\left(\frac{1}{2}\right)^n
\end{aligned}
$$
$$
\Rightarrow \frac{25}{100}=\left(\frac{1}{2}\right)^n \Rightarrow n=2
$$
$\therefore$ Total time is $2 \times 1600=3200$ year
$$
\begin{aligned}
N & =N_0\left(\frac{1}{2}\right)^n \\
\Rightarrow \quad \frac{N}{N_0} & =\left(\frac{1}{2}\right)^n
\end{aligned}
$$
$$
\Rightarrow \frac{25}{100}=\left(\frac{1}{2}\right)^n \Rightarrow n=2
$$
$\therefore$ Total time is $2 \times 1600=3200$ year
Looking for more such questions to practice?
Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.