Answer:
After 28 sec 7.5 grams of Be will be left
Explanation:
Given data:
Total amount of Be = 30 g
Half life of Be = 14 sec
Mass left after 28 sec = ?
Solution:
First of all we will calculate the number of half lives in 28 sec.
Number of half lives = T elapsed / half life
Number of half lives = 28 sec / 14 sec
Number of half lives = 2
AT time zero = 30 g
At first half life = 30 g/2 = 15 g
At second half life = 15 g/ 2 = 7.5 g
So after 28 sec 7.5 grams of Be will be left.
