What does the period number on the periodic table correspond to?

The continuous release of nuclear energy caused when one fission reaction triggered more nuclear reactions is a

Astudent is trying to create a table that compares hypotheses, theories, and laws. hypothesis theory law do scientific researchers formulate it? yes yes yes does it explain why things happen? yes yes no yes yes yes is it used to make predictions? no yes yes which of the following questions would most likely fill the blank in the table? is it an intelligent guess? is it newly formulated? is it based on observations? has it been proved?

Chemistry worksheet - i am not sure what they are asking for exactly?