A patient is given 40.00 mg of iodine-131 (131I) 131 53

The half-life of 53 I is 8 days.

How many milligrams of the 131I remains in the

patient after 32 days?

2.5 mg

Explanation:

We are given;

Original mass of I-131 is 40.0 mg Half life of I-131 is 8 days Number of days 32 days

We are required to determine the mass that will remain;

Using the formula;

N = N₀ * 0.5^n

where, N is the remaining mass, N₀ is the original mass, and n is the number of half lives.

Therefore;

n = time : half life

= 32 days : 8 days

= 4

Therefore;

Remaining mass = 40.0 mg * 0.5^4

= 2.5 mg

Hence, the remaining mass of I-131 after 32 days is 2.5 mg