Question
Question: The half life period of a radioactive substance is 5 min. The amount of substance decayed in 20 min ...
The half life period of a radioactive substance is 5 min. The amount of substance decayed in 20 min will be.
A
93.75%
B
75%
C
25%
D
6.25%
Answer
93.75%
Explanation
Solution
Number of half lives in 20 min = n =520=4
Fraction of material remains after four half lives =161
Hence fraction that decays =1−161=1615=93.75%