Question

THE HALF LIFE OF A RADIOACTIVE ELEMENT IS 10 HOURS.
HOW MUCH WILL BE LEFT AFTER 4 HOURS IN 1 GRAM ATOM SAMPLE ?

Answer 1

4/10=> 2/5 or => 0.4 half lives.
after 0.4 half lives,
the amount would be left=> (1/2)^0.4
((1/2)^0.4)*1 gm
=> 1/2^0.% gms

Answer 2

Answer: 0.7580 grams will be left after 4 hours.

Explanation:

Mass of the element = 1 g

half life = 10 hours

$t_{\frac{1}{2}}=10 hour=\frac{0.693}{\lambda }$

$\lambda =0.0693 hour^{-1}$

$N=\times N_oe^{-\lambda t}$

$\log N=\frac{-\lambda t}{2.303}+\log N_o$

$N=0.7580 grams$

0.7580 grams will be left after 4 hours.