The radioactive decay of a certain isotope of lead is a first-order process that has a half-life of 242 minutes at a certain temperature. At this temperature, what percentage of the original concentration will be left after 45.0 minutes? (A) 0.29 % (В) 1.29 % (C) 87.9 % (D) 81.4 % (E) 18.6 %

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