A chemical compound used in water treatment has a half-life of 8 years. The initial amount of the compound is 80 grams. How much of the compound will remain after 16 years?
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✓ Correct answer: B. 20 gramsThe compound undergoes radioactive decay, reducing by half every 8 years. Therefore after 16 years, which represent two half-lives: \ul{\begin{array}{rl} \text{First half-life:} & 80 \text{ grams} \to 40 \text{ grams} \ \text{Second half-life:} & 40 \text{ grams} \to 20 \text{ grams} \ \end{array}} \ Therefore, the compound reduces to 20 grams after 16 years.
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