JEE MAIN - Chemistry (2004 - No. 43)
The half – life of a radioisotope is four hours. If the initial mass of the isotope was 200 g, the
mass remaining after 24 hours undecayed is
1.042 g
4.167 g
3.125 g
2.084 g
Пояснення
$${N_t} = {N_0}{\left( {{1 \over 2}} \right)^n}$$ where $$n$$ is number of half life periods.
$$n = {{Total\,\,time} \over {half\,\,life}} = {{24} \over 4} = 6$$
$$\therefore$$ $$\,\,\,\,\,{N_t} = 200{\left( {{1 \over 2}} \right)^6} = 3.125g.$$
$$n = {{Total\,\,time} \over {half\,\,life}} = {{24} \over 4} = 6$$
$$\therefore$$ $$\,\,\,\,\,{N_t} = 200{\left( {{1 \over 2}} \right)^6} = 3.125g.$$