The half-life for a 100-gram sample of radioactive element X is 5 days. How much of element X remains after 10 days have passed?
Starting amount Day5 Day10
100 g
a
25 g
b
50 g
c
75 g
d
100 g
After 5 days have passed, half of the radioactive element X remains, so there will be 50 grams remaining.
After another 5 days have passed (10 days total), another half of the remaining element X will decay, resulting in 25 grams remaining.
Therefore, after 10 days have passed, 25 grams of element X remains.