Half-life is the time a. for half of a material to decay into energy b. for half of a material to decay into free protons, neutrons, and electrons c. for half of a material to decay into a new material d. it takes to get out of school

Explanation:

The half life of a radioactive substance is the time in which the activity of the radioactive substance becomes half of its initial activity.

Or

The time in which the amount of radioactive substance becomes half of its initial amount in a sample.

It is denoted by T .

The relation between the decay constant and the half life is given by

frequency or wavelenth of em radiation in a vacuum

it would be c. predictability