Question
How much of 5.00 gram of polonium will decay in one year? The halflife of polonium is 138 days.

4.50 g

4.20 g

5.40 g

None of these
medium
Solution
4.20 g
The decay constant of polonium is
= 0.00502 day^{–1}.
If N_{0} be the number of atoms, or amount of radioactive substance, initially (at t = 0), then the amount left after time t is given by
Here N_{0} = 5.00 g and t = one year = 365 days.
.
amount of polonium decayed is
.
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