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First Order Half Life

Q. Fluorine-18 undergoes positron emission with a half-life of 1.0 × 10^2 minutes. If a patient is given a 248 mg dose for a PET scan, how long will it take for the amount of fluorine-18 to drop to 83 mg? (Assume that none of the fluorine is excreted from the body.

Solved • May 5, 2020

First Order Half Life

Q. Potassium-40 decays to argon-40 with a half-life of 1.27 x 10^9 yr. The age of a mineral sample that has a mass ratio of 40-Ar to 40-K of 0.712 is ______ yr.

Solved • May 2, 2020

First Order Half Life

Q. The accompanying graph illustrates the decay of 88-Mo, which decays via positron emission. (Figure 1). What is the rate constant for the decay? Express your answer using one significant figure.

Solved • May 1, 2020

First Order Half Life

Q. The accompanying graph illustrates the decay of 88-Mo, which decays via positron emission. (Figure 1) What fraction of the original sample 8-Mo remains after 12 minutes? Express your answer using two significant figures.

Solved • May 1, 2020

First Order Half Life

Q. The accompanying graph illustrates the decay of 88-Mo, which decays via positron emission. (Figure 1). What is the half-life of the decay? Express your answer using one significant figure.

Solved • May 1, 2020

First Order Half Life

Q. The cloth shroud from around a mummy is found to have a 14-C activity of 8.3 disintegrations per minute per gram of carbon as compared with living organisms that undergo 16.3 disintegrations per minute per gram of carbon. From the half-life for 14-C decay, 5715 yr, calculate the age of the shroud. Express your answer using two significant figures.

Solved • May 1, 2020

First Order Half Life

Q. Potassium-40 decays to argon-40 with a half-life of 1.27 x 10^9 yr. What is the age of a rock in which the mass ratio of 40-Ar to 40-K is 4.2? Express your answer using two significant figures.

Solved • May 1, 2020