posted by .

use logic and simple math to determine how long it will take for a sample of potassium- 42 to decay from 8mg to 0.25mg if the half-life of this radioactive isotope is 124 hours

  • chemistry -

    8mg to 0.25 mg means how many half lives.
    1 half life = 4 mg remain
    2 half lives = 2 mg remain
    3 half lives = 1 mg remain
    4 half lives = 0.5 mg remain
    5 half lives = 0.25 mg remain.
    It takes 124 hours for a half life; therefore, it must take 124 x 5 for the 5 half lives.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. chemistry

    How long will it take for 25% of the C-14 atoms in a sample of C-14 to decay?
  2. Chemistry

    Gallium65, a radioactive isotope of gallium, decays by first order-kinetics. The half-life of this isotope is 15.2 min. How long would it take for 7/8 of a sample of this isotope to decay?
  3. Chemistry

    How many half lives will it take for a sample of a radioactive isotope containing 20000 radioactive nuclei to decay to 2000 radioactive nuclei
  4. Math - D.E.Q.

    The half-life of a radioactive isotope is the amount of time it takes for a quantity of radioactive material to decay to one-half of its original amount. i) The half-life of Carbon 14 (C-14) is 5230 years. Determine the decay-rate …
  5. Science

    If a radioactive isotope has half life of 5 days,how long will it take for its radioactive strength to be a maximum of one thousandth,(1/1000) of its original value?
  6. math

    An unknown radioactive element decays into non-radioactive substances. In 100 days the radioactivity of a sample decreases by 64 percent. a)(a) What is the half-life of the element?
  7. Science- Radioactive Dating

    Which of the following statements about radioactive dating is true?
  8. chem

    How long does it take for 10.0 g of a radioactive isotope to decay to 1.25 g if its half-life is 17.0 d?
  9. Physics (Inside the atom)

    A sample of radioactive isotope I is to be used for medical diagnosis of the kidneys. The isotope has a half-life of 8.0 days, and the sample is required to have an activity of 8 x 10^5 per second at the time it is given to the patient. …
  10. Calculus

    The rate of decay is proportional to the mass for radioactive material. For a certain radioactive isotope, this rate of decay is given by the differential equation dm/dt = -.022m, where m is the mass of the isotope in mg and t is the …

More Similar Questions