Review Conceptual Example 11 before starting to solve this problem. The number of unstable nuclei remaining after a time t = 5.00 yr is N, and the number present initially is N₀. Find the ratio N/N₀ for

(a)  (half-life = 5730 yr),

(b)  (half-life = 122.2 s; use t = 1.00 h, since otherwise the answer is out of the range of your calculator), and

(c)  (half-life = 12.33 yr). Verify that your answers are consistent with the reasoning in Conceptual Example 11.

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