1. Your original sample of Manganese-56 is 20.0 mg. How much is left after 3 half lives? Remember to round to the correct number of significant figures and use units (mg).

2. Tritium is a radioactive form of hydrogen with a half-life of 12.3 years. How much of the 48.0 mg of tritium is still radioactive after 98.4 years?

Make sure to round to the correct number of significant figures and use units (mg).

3. How much of a 1.00 g polonium-214 sample remains after 818 microseconds? The half-life of polonium-214 is 163.7 microseconds.

Make sure to round to the correct number of significant figures and use units (g).