An isotope of sodium, 24Na, has a half-life of 15 hours. A sample of this isotope...
The radioactive isotope thorium 234 has a half-life of approximately 578 hours. (a) If a sample has a mass of 67 milligrams, find an expression for the mass after t hours. Q(t) = 67e-0.0011997 (b) How much will remain after 85 hours? (Round your answer to one decimal place.) 60.5 mg (c) When will the initial mass decay to 20 milligrams? (Round your answer to one decimal place.) 1008.3 x hr
Radium-226. a radium isotope, has a half-life (the time it takes half of the isotope to decay) of about 1620 years. A sample of radium-226 has a mass of 30 grams. Which of the following equations expresses the number of grams, g, of this sample that will be left after tyears? OA 1620 9= 30 -15.00 OB oc 9 = 30 - 157620 OD 9=301620
A radioactive sample contains 1.55g of an isotope with a half-life of 3.7 days.Part A:What mass of the isotope will remain after 5.8 days? (Assume no excretion of the nuclide from the body.)Express your answer using two significant figures.
A) 13N decays with a half-life of approximately 10 min to produce 13C, a stable isotope of carbon. For a 1.0g sample of 13N, after one half-life, what mass of 13N remains? What has happened to the remaining mass? B) 223Ra decays by alpha emission with a half-life of 11.43 days. For a 1.0g sample of 223Ra, after one half-life, what mass of 223Ra remains? What has happened to the remaining mass?
A particular radioactive isotope has a half-life of (2.50+A) hours. If you have (24.5+B) g of the isotope at 10:00 AM, how much will you have at 7:30PM? Give your answer in grams (g) and with 3 significant figures A= 2 B= 2
The half-life of caffeine in the human body is about 6.5 hours. A cup of coffee has about 105 mg of caffeine. a. Write an equation for the amount of caffeine in a person's body after drinking a cup of coffee? Let C be the milligrams of caffeine in the body after thours. b. How much caffeine will remain after 10 hours? mg c. How long until there are only 20 mg remaining? hours
Assume that a hypothetical radioactive isotope has a half-life of 15 years. A 100.0-mCi sample of this radioactive isotope is deposited in a lead container. How long it will take until the activity of this sample is reduced to 1.00 mCi?
Yttrium-90 is a radioactive isotope used to treat tumors in the liver. Y90 has a half-life of 2.67 days. If a patient has 3.92 ?g of Y90 in her body 1.35 days after treatment, what mass of Y90 was used in her dose? Assume that none of the yttrium was passed normally out of her body.
Sodium-24 is used to study blood circulation and has a half-life of 15 hours. Which one of the following statements is true? a. It is not possible to know exactly how much remains after 45 hours because the rate of decay depends on the initial amount. b. After 45 hours have elapsed, all of the nuclide will have decayed. c. After 45 hours have elapsed, 1/8 of the original amount remains d. After 45 hours have elapsed, 1/4 of the...
A 0.0116-g sample of a radioactive isotope with a half life of 1.3x109 years decays at the rate of 2.9x104 disintegrations per minute. Calculate the molar mass of the isotope. Enter your answer in scientific notation. (g/mol)