P32 a radioisotope used to treat leukemia has a halflife of

P-32, a radioisotope used to treat leukemia, has a half-life of 14.3 days. If a sample contains 8.0 mg of P-32, how many milligrams of P-32 remain after 42.9 days? 0.50 mg 1.0 mg 2.0 mg 3.0 mg 4.0 mg

Solution

Answer: 1mg

Number of half lives = 49.9/14.3 = 3

If the initial concentration of P-32 is 8 mg then after 3 half lives it will be 1mg