Using the graph from the previous question, estimate the mass of polonium-210 remaining after 300 days.

There are two ways to approach this: 1. **Extrapolating the graph:** Find 300 on the time (x) axis. Follow the line up to where the curve would be if it continued. Then read across to the mass (y) axis. This gives a value around 125 mg. 2. **Using half-life:** The half-life is the time it takes for the mass to halve. - Starts at 600 mg. - Half of 600 is 300 mg. The time to reach 300 mg is approximately 140 days. So the half-life is ~140 days. - After another half-life (at 140 + 140 = 280 days), the mass will halve again: 300 mg / 2 = 150 mg. - 300 days is a little after 280 days, so the mass will be a little less than 150 mg. The value from the graph of ~125 mg is a reasonable estimate.