A radioactive substance of mass 768g has a half life of 3 years. After how many years does this substance leave only 6g undecayed?
-
21
- 18
- 15
- 12
The correct answer is: A
Explanation
\(768 \to 384 \to 192 \to 96 \to 48 \to 24 \to 12 \to 6\)7 x 3 = 21yrs