Question

The first radioisotope to be put to use medically was iodine-131.

Answer 1

The first radioisotope to be put to use medically was iodine-131 is True. It was discovered in 1938 by Glenn Seaborg and John Livingood. It is linked to medical diagnosis and treatments, natural gas production and nuclear energy. 
The following statement: "Proponents of nuclear energy believe that it is a safer, cleaner, and more efficient way of making electricity than coal-fired power plants" is True.  Nuclear energy is energy that is stored in the nucleus of an atom. It is used in the generation of electricity.