Avogadro's law relates the moles of a gas with its volume. The volume of a gas is directely proportional to its moles when temperature and pressure of the gas remains constant. The law is:
V₁n₂ = V₂n₁
<em>Where V is volume and n are moles of 1, initial state and 2, final state of the gas.</em>
It is really easy if you look up an electron configuration table (one that looks like a periodic table) and then just go down the rows left to right, top to bottom, and just stop when you get to where the element is on the table.