Question

Krypton-79 has a half-life of 35 hours. how many half-lives have passed after 105 hours?

Answer 1

The number of half -lives that has passed after 105  hours  for krypton-79 that has  half-life of 35 hours is calculated as below

if 1 half life = 35 hours

what about 105 hours = ? half-lives

= (1 half life  x105  hours) /35 hours = 3 half-lives  has passed after 105 hours