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Half-Life Question – Type 3
Half-Life Question – Type 3: What’s the mass of the original sample?
After 3 half-lives, 12.5 grams of an original sample remains unchanged. What is the mass of the original sample?
“Undo” the half-lives 3 times: 12.5 X 2 = 25 : 1 half-life 25 x 2 = 50 : 2 half-lives 50 x 2 = 100 : 3 half-lives
-OR-
12.5 x 2 x 2 x 2 = 100
The original sample was 100g!
UNIT 12: NUCLEAR CHEMISTRY © 494
