Calcium (Ca) has an atomic number of 20. It can form an ion by losing 2 electrons. What would its charge be?
A. 18
B. 22
C. 2+
D. 2-

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

May someone me with these science questions

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?