Iodine-131 is a radioactive isotope with a half-life of 8 days. How many grams of a 64 gram sample of Iodine-131 will remain after 24 days?

A) 56g

B) 48g

C) 32g

D) 8g

D) 8g

Explanation:

Given dа ta:

Half life of I-131 = 8 days

Total amount of sample = 64 g

Amount remain after 24 days = ?

Solution:

Number of half lives = T elapsed / Half life

Number of half lives = 24 days / 8 days

Number of half lives = 3

At time zero = 64 g

At 1st half life = 64 g / 2 = 32 g

At second half life = 32 g / 2 = 16 g

At third half life = 16 g / 2 = 8 g