Question

what is a half - life?

a. the time it takes for a sample to no longer be radioactive

b. the amount of material that remains after a fixed amount of time

c. the time it takes for half of a radioactive sample to decay

d. the amount of material needed to determine the age of an object

Explanation:

Half - life is defined as the time required for half of the atoms in a radioactive sample to decay. Option A is incorrect as a sample may never completely lose radioactivity. Option B refers to the remaining amount of material after a time, not the half - life. Option D is about the amount of material for age - determination, not half - life.

Answer:

C. The time it takes for half of a radioactive sample to decay