Suppose a sample of a radioactive substance weighs 32 mg. One year later, the sample weighs 25.5 mg. What is the half-life of this substance?
A 50.0 mg sample of an unknown radioactive substance was placed in storage and its mass measured periodically. After 70.9 days70.9 days, the amount of radioactive substance had decreased to 3.13 mg. What is the half-life of the unknown radioactive substance? half-life: days
Need help with these problems. 1. A doctor prescribes 150 milligrams of a therapeutic drug that decays by about 10% each hour. Write an exponential model representing the amount A in milligrams of the drug remaining in the patient's system after t hours. 2. Suppose a sample of a radioactive substance weighs 38 mg. One year later, the sample weighs 23.5mg. What is the half-life of this substance? 3. Carbon-14 has a half-life of 5,730 years. A fossil is found...
A 100-mg sample of a radioactive isotope is obtained. After 33.5 minutes, only 3.10 mg remains. What is the half-life of the isotope? min
A sample of a certain radioactive substance is prepared, and its initial activity is 4 µCi. After 2.4 hours, the activity is measured to be 1 µCi. What is the half-life of this material?
A scientist begins with 250 grams of a radioactive substance. After 250 minutes, the sample has decayed to 36 grams. Write an exponential equation f(t) representing this situation. (Let f be the amount of radioactive substance in grams and t be the time in minutes.) f(t) 250e 0.0087t x To the nearest minute, what is the half-life of this substance? 89 min Use the model for continuous exponential decay, y = Ao e-kt, where y is the amount of radioactive...
A toxic radioactive substance with a density of 8 milligrams per square centimeter is detected in the ventilating ducts of a nuclear processing building that was used 35 years ago. The density of the radioactive substance when it was deposited 35 years ago was approximately _ mg/cm Between 2005 and 2009, the average rate of inflation was about 2.8% per year. If a cart of groceries cost $180 in 2005, what did it cost in 2009? A cart of groceries...
The decay of radioactive cadmium follows first-order kinetics. A sample of radioactive cadmium has a half life of 15 days. If you have a sample that originally weighed 40 g and later weighs 2.5 g, how much time elapsed between the initial and final masses? A. 45 days B. 600 days C. 60 days D. 100 days
You have an unknown radioactive material. If you start out with a 405 mg sample, and after 120 minutes, 53.1 mg remains, what is the half life?
A) You are using a Geiger counter to measure the activity of a radioactive substance over the course of several minutes. If the reading of 400. counts has diminished to 100. counts after 48.2 minutes , what is the half-life of this substance? B) An unknown radioactive substance has a half-life of 3.20 hours . If 24.3 g of the substance is currently present, what mass A0 was present 8.00 hours ago? C) Americium-241 is used in some smoke detectors....
231 A 60 mg sample of a radioactive isotope decays to 50 mg after 4.7 days. a) Determine the half-life. b) How long will it take for the amount of the isotope to decrease to 20 mg?