Answer:
The correct answer is - A. 12.5 gram.
Step-by-step explanation:
Given:
The initial amount of sample = 400 gram
the half-life cycle = 3 days
after 15 days remain value = ?
Solution:
The number of half-lives in 15 days = 15/3
= 5 half-lives
the remaining amount of sample after one half-life 3 days = 400/2 = 200
the remaining amount of sample after 2nd half-life or 6 days= 200/2 = 100
the remaining amount of sample after 3rd half-life or 9 days= 100/2 = 50
the remaining amount of sample after 4th half-life or 12 days= 50/2 = 25
the remaining amount of sample after 5th half-life or 15 days= 25/2 = 12.5 gram
Thus, the correct answer is = 12.5 g.