Question

Fraction of tritium left after $125$ years (half life of tritium is $12.5$ years) is

• A. $1/1024$
• B. $1/2048$
• C. $1/4096$
• D. $1/8192$

Answer 1

The correct option is A $1/1024$

If initial amount is $N_0$ then remaining amount$\left(N\right)$ after $n$ half lives is given as $N=N_0(\frac{1}{2}{)}^n$

Number of half lives $n=125/12.5=10$

So fraction of left amount will be $\frac{N}{N_0}=(\frac{1}{2}{)}^{10}=\frac{1}{1024}$