After three half-lives, % of uranium-238 isotopes have decayed.
Question
After three half-lives, % of uranium-238 isotopes have decayed.
Solution
The half-life of a substance is the time it takes for half of the substance to decay.
- After one half-life, 50% of the uranium-238 isotopes have decayed, leaving 50% remaining.
- After two half-lives, half of the remaining 50% (or 25%) have decayed, leaving 25% remaining.
- After three half-lives, half of the remaining 25% (or 12.5%) have decayed, leaving 12.5% remaining.
So, after three half-lives, 100% - 12.5% = 87.5% of uranium-238 isotopes have decayed.
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