Which of the given elements would most likely be not radioactive?

Question

1. Be

2. Po

3. I

4. Co

Answer 1

3. I....i think. its been a while since chem lol

Answer 2

Berylium would be most likely not to be radioactive.  It only has one stable isotope, and it has the lowest atomic number, Z.

At low values of Z the number of neutrons often equals the number of protons producing stable isotopes.  As the atomic number increases, the mass number increases more rapidly, which means that there are many more neutrons than protons and a much greater chance that there will be unstable isotopes formed.  These unstable isotopes are radioactive.