The length of time required for half of the radioactive atoms in a sample to decay is its

HALF LIFE.

Explanation:

The half life of a radioactive element refers to the length of time that is required for the half of the atoms of a particular sample of radioactive element to decay. For instance a radioactive element that a mass of 120 g and a half life of 2 years will be reduce to 60 g in two years. Half life is usually used to measure the rate of disintegration of an unstable isotope. The principle of half life of radioactive elements can be used to determine the relative ages of rocks.  

false because ozone (o3) depletion does not cause global warming, but both of these environmental problems have a common cause: human activities that release pollutants into the atmosphere altering it.

global warming is caused primarily by putting too much carbon dioxide into the atmosphere when coal, oil, and natural gas are burned to generate electricity or to run our cars.

explanation: