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Praxis II General Science

Category - Major Ideas

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If a particular element has a half-life of 25 years, how long will it take to reach less than 1% of its original concentration?

175 years
250 years
50 years
25 years
500 years

Explanation

Answer: A - If an element has a half-life of 25 years, then it will need 7 half-lives to reach less than 1% in concentration. This can be calculated by performing 1/(2⁷).

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