Question

A given sample contains $16gms$ of radioactive material whose half life is two days. The quantity of radioactive material that remains in that sample after $32$ days will be

• A. $\frac{1}{2}gm$
• B. $\frac{1}{8}gm$
• C. $\frac{1}{4}gm$
• D. less than $1mg$

Answer 1

The correct option is D less than $1mg$

Total half life in $32$ days is $=\frac{32}{2}=16$

The quantity of radioactive material that remains in that sample after $32$ days will be $16\times 1/2^{\left(32/2\right)}=16\times 1/2^{16}=0.25mg$