Question

The half-life of radium is $1600yr$. What fraction of sample of radium will be disintegrated after $6400yr$?

• A. $\frac{13}{16}$
• B. $\frac{1}{16}$
• C. $\frac{8}{17}$
• D. $\frac{15}{16}$

Answer 1

Answer: (B)

As radioactive decay is first-order kinetic half-life given is 1600 years in 6400 no. of half-life is
$<br/>n=\frac{6400}{1600}=4<br/>$
fraction of element remains after $n$ half life is given $by=\frac{1}{2^n}$ Hence fraction of radium remains after 4 half life $=\frac{1}{2^4}=\frac{1}{16}$.