Phosphorus-32 is used in biochemical studies to follow the pathway taken by

metabolites. Its half-life is 14.3 days. A vial containing 10µg of P-32 is accidentally

spilled into a sink. a) How long will it take P-32 in the drain to exhibit 65% of its original activity?

b) How many atoms of P-32 remain in the sink after 785 days?