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?
a
12.5 g
b
50 g
c
10o g - no change
d
25 g
The half-life of the radioactive element X is 5 days, which means that after every 5 days, the amount of element X is halved.
After 5 days, half of the original sample remains, which is 100g/2 = 50g.
After another 5 days (10 days in total), another half of the remaining sample will be gone, leaving 50g/2 = 25g.
Therefore, the amount of element X that remains after 10 days is 25g.
The answer is d) 25 g.