Answer:
Half life of phosphorous-32 = 14 days
Explanation:
Given data:
Total mass of phosphorous-32 = 2.0 g
After 42 days mass left = 0.25 g
Half life of phosphorous-32 = ?
Solution:
First of all we will calculate the number of half lives passed.
At time zero = 2.0 g
At first half life = 2.0 g/2 = 1.0 g
At 2nd half life = 1.0 g/2 = 0.5 g
At 3rd half life = 0.5 g/2 = 0.25 g
Half life:
Half life = T elapsed / half lives
Half life = 42 days/ 3
Half life = 14 days