Question

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

Answer 1

D) 8g

Step-by-step explanation:

Given data:

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