Technetium-99m is a radioactive isotope commonly used in medicine as a radioactive tracer. A radioactive tracer is an isotope injected into the body to help create images for diagnosis of health problems. Technetium-99m has a half-life of 6 hours. If a patient receives a dose of technetium-99m one morning, about what percentage of the technetium-99m will be left in the patient's body 12
hours later?
A
6.25%
B
12.5%
С
25.0%
D
93.8%

C. 25.0%

Explanation:

Radioactive decay of an atom follows the equation:

ln[A] = -kt + ln[A]₀

Where [A] could be taken as an amount of radioactive atom after time t,

k is rate constant = ln 2 / Half-Life = ln 2 / 6hours = 0.1155hours⁻¹

[A]₀ is initial amount of the isotope = 100%

Replacing:

ln[A] = -0.1155hours⁻¹ *12hours+ ln[100%]

ln[A] = 3.2192

[A] = 25.0%

Right solution is:

C. 25.0%

the independent variable, the one that is intentionally manipulated, is whether or not the car hits the barrier.

the dependent variable, the one that you measure the response in, is the distance that the washers travel.