Question

If the half-life of iodine-131 is 8 days, how much of a 5.00 sample is left after 32 days?

A) 0.31

B) 2.5

C) 1.25

D) 0.62

Answer 1

Option A, 0.31

Step-by-step explanation:

n = Time taken / half life

n = 32/ 8

= 4

Remaining fraction = 1/2^n

= 1/2⁴

= 1/16

Amount of iodine-131 left = 1/16 × 5

= 0.3125