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
The half-life of element X is 5 days, which means that after every 5 days, half of the sample will decay.
After 5 days, half of the sample would remain, so 100g * 0.5 = 50g
After another 5 days (total of 10 days), half of the remaining sample would decay, so 50g * 0.5 = 25g.
Therefore, after 10 days, 25 grams of element X would remain.