• 24Pu has a half-life of 14 years. If we start with 100 grams of 241Pu how much will remain
after 42 years and how much would have decayed?

The amount of sample remain  after 48 years is 12.5 g.

Amount of sample decayed = 100 g- 12.5 g = 87.5 g

Explanation:

Given data:

Half life of Pu²⁴¹ = 14 years

Total amount of sample = 100 g

Sample remain after 42 years = ?

Sample decayed = ?

Solution:

First of all we will calculate the number of half lives.

Number of Half lives = T elapsed / half life

Number of Half lives = 42 years / 14 years

Number of Half lives = 3

At time zero = 100 g

At first half life = 100 g /2 = 50 g

At second half life = 50 g/2 = 25 g

At third half life = 25 g/ 2 = 12.5 g

So the amount of sample remain  after 48 years is 12.5 g.

Amount of sample decayed = 100 g- 12.5 g = 87.5 g