The time that it takes a macroscopic sample of a radioisotope to decay to one-half its original activity is known as the
A) reaction rate.
B) kinetics.
C) half-life.
D) lifetime.
E) decay rate.

Question

Quizplus · Accepted Answer

The half-life of a radioisotope is the time it takes for half of the radioactive atoms in a sample to decay, which directly matches the definition provided in the question.

The Time That It Takes a Macroscopic Sample of a Radioisotope