Question

Iodine 131 decays with a half-life of 8.02 days in a sample initially containing 5 mg of I131. What mass remains after 6.01 days?

a) 2.5 mg
b) 3.75 mg
c) 1.25 mg
d) 5.0 mg

Answer 1

Iodine-131 decays with a half-life of 8.02 days. After 6.01 days, the mass remaining can be calculated using the formula: Remaining mass = Initial mass × (1/2)^(Number of half-lives). The mass that remains after 6.01 days is approximately 3.27 mg.

Step-by-step explanation:

In radioactive decay, the amount of a radioactive substance decreases over time. The half-life is the time it takes for half of the substance to decay. In this case, iodine-131 has a half-life of 8.02 days. After 6.01 days, we need to find the mass that remains.

Since the half-life is 8.02 days, we can determine how many half-lives have passed by dividing the elapsed time (6.01 days) by the half-life.
6.01 days ÷ 8.02 days/half-life = 0.748 half-lives.

Each half-life reduces the mass by half. So, the remaining mass can be calculated as:

Remaining mass = Initial mass × (1/2)Number of half-lives

Remaining mass = 5 mg × (1/2)0.748 = 5 mg × 0.654 = 3.27 mg.

Therefore, the mass that remains after 6.01 days is approximately 3.27 mg. So, the correct answer is d) 3.27 mg.