The half-life of ⁴²K is 12.5 h.How much will remain after 75 h if the original sample contained 256 g of ⁴²K?

Name: The half-life of 42 K is 12.5 h.How much will remain after 75 h if the original sample contained 256 g of 42 K?
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Quizplus · Accepted Answer

After 75 hours, which is 6 half-lives (75 h / 12.5 h/half-life = 6 half-lives), the amount of substance remaining is calculated by dividing the original amount by 2^6 (since each half-life halves the amount). Thus, 256 g / 2^6 = 256 g / 64 = 4 g.

The Half-Life of 42K Is 12

The Half-Life of ⁴²K Is 12