If the half life of substance is 5 years, then the total amount of the substance left after 15 years, when…
If the half life of substance is 5 years, then the total amount of the substance left after 15 years, when initial amount is 64 gms is
6 gm
8 gm
10 gm
12 gm
Solution
Initial amount $=64 \mathrm{gms}$
Half life period $=5$ : years
$\therefore \quad$ Amount of substance left after 5 years $=\frac{64}{2}=32 \mathrm{gms}$
Amount of substance left after 10 years $=\frac{32}{2}=16 \mathrm{gms}$
Amount of substance left after 15 years $=\frac{16}{2}=8 \mathrm{gms}$