A 9.9-g sample of iodine-131 is stored for exactly 3 weeks .If the decay constant is 0.0861 day^-¹,What mass of the isotope remains?

Question

Quizplus · Accepted Answer

We can use the radioactive decay formula to find the mass of remaining iodine-131:

m = m0 * e^(-kt)

where:
m0 = initial mass of iodine-131 = 9.9 g
k = decay constant = 0.0861 day^-1
t = time = 3 weeks = 21 days

Substituting these values:

m = 9.9 * e^(-0.0861*21)
  = 9.9 * e^(-1.809)
  = 1.55 g

Therefore, the mass of remaining iodine-131 is approximately 1.6 g, which corresponds to choice C.

A 99-G Sample of Iodine-131 Is Stored for Exactly 3 Weeks