Posted by Heena on Sunday, November 14, 2010 at 12:45am.
Draw a graph to show the decay of 32g of plutonium241. Use the graph to find the mass of plutonium241 after 20 years.

Physics  drwls, Sunday, November 14, 2010 at 4:39am
We don't draw graphs for students here. I suggest you use semilogarithmic graph paper, with a logarithmic mass scale, and a linear scale for time. The decay curve will then be a straight line.
The half life of Pu241 is 13 years.
M = 32*(2)^(t/13)
LogM = Log32 (t/13)*Log2
= 1.505  0.02316 t
(using log to base 10)
= 1.042 when t = 20 years
M = 11 g
About 1/3 will remain after 20 years.