Question

Iodine-131 has a half-life of 8 days. If the amount of iodine-131 in the original sample is 8 g, how much iodine-131 will remain after 24 days?

a) 1 g
b) 2 g
c) 4 g
d) 8 g

Answer 1

After 24 days, which is equivalent to three half-lives of iodine-131, the amount remaining from the original sample of 8 g would be 1 g.

Step-by-step explanation:

The amount of iodine-131 remaining after a certain number of days can be calculated using its half-life. Iodine-131 has a half-life of 8 days. To find out how much remains after 24 days, we determine how many half-lives have passed in 24 days, and then we can calculate the remaining amount of iodine-131.

Since 24 days is three times the half-life of 8 days, we can calculate the remaining amount as follows:

• After the first 8 days (1 half-life), half of the original amount would remain, so from 8 g we would have 4 g.
• After 16 days (2 half-lives), another half would decay, leaving us with 2 g.
• After 24 days (3 half-lives), yet another half would decay, leaving us with 1 g.

Therefore, the correct answer is a) 1 g.