How many atoms of Magnesium are needed to form 37g of Magnesium oxide?

Which other elements contain the same number of outer electrons as sodium

Consider this initial-rate data at a certain temperature for the reaction described by

What is conserved in the reaction shown below? h2(g) + cl2 (g) --> 2hcl(g)a. mass onlyb. mass and moles onlyc. mass, moles, and molecules onlyd. mass, moles, molecules, and volume