Three of the Carbon isotopes (C) are found in nature.
The rest of the carbon isotopes are only of laboratory interest.
So simple arithmetic should tell us the number of neutrons. Carbon 10 would have 4 neutrons and Carbon 11 would have 5 neutrons, and so on.
What should catch your attention is the nature of the various carbon isotopes.
To understand this process we must first understand a little bit about the atoms themselves and how they get their names.
It is called "Carbon-12," which is abbreviated "C." The fact that the atom has six protons is what makes it carbon.
The units of time used in problems like these usually are proportional to the life span of the organisms of the population.
For populations of bacteria, hours or days are common, and for people, years are common.
When the interest earned on an investment is simple, the investor only earns interest on his initial investment.
The interest earned with simple interest is the product of the interest rate, the time since the investment (usually measured in years), and the principal.
Thus the breakdown of radioactive atoms is a self-corrective process; those Isotopes which have too many neutrons loose a neutron in the beta decay, and those Isotopes which have too few neutrons gain a neutron in the positron decay.