Question

How much grams of a substance will be left after 2 hours if its half life is 15 minutes?

Answer 1

`=M/256g`, where M = initial mass

Explanation:

Let the initial mass be M g,
Half life period is 15 min
In 2 hrs or 120 min there will be`120/15=8` half life periods.
For each half life the mass is halved, so after 2 hrs i.e. after 8 half life periods the mass will be `=Mxx(1/2)^8g=M/256g`