16. What is the percentage of nitrogen in N2O? Show all calculations leading to an answer.
 17. How many non-bonding electrons does phosphorus have?
 18. Complete and balance this reaction: sulfuric acid reacts with barium chloride
 19. Identify the precipitate in this reaction: calcium nitrate reacts with sodium phosphate.
 20. The following is a Limiting Reactant problem:
 Magnesium nitride is formed in the reaction of magnesium metal with nitrogen gas in this reaction: 3 Mg(s) + N2(g)  Mg3N2(s)
 How many grams of product are formed from 2.0 mol of N2 (g) and 8.0 mol of Mg(s)? Show all calculations leading to an answer.