What is the role of neutrons in an atom? ?

Neutrons are found only in the nucleus of the atom, where they play an important role in keeping the atom stable. Since protons are positively charged, there is an incredibly strong repulsive force between all the protons in a nucleus.

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.