Answer: Elements in the last period are radioactive.
Explanation:
For metals, reactivity increases down a group and from right to left across a period. Non metals, reactivitt increases up a grouo and from left to right across a period. Francium is the most reactive metal and fluorine is the most reactive non-metal.
Na because its a metal. Metals are the best conductors. S and Ne are nonmetals. and Ge is a metalloid. (Metalloids are semi conductors)
