1) Titanium Dioxide, what's the percent of oxygen by mass?, in Titanium Dioxide 2) By mass, nicotine is 74.0% carbon, 8.7% hydrogen and 17.3% nitrogen, it's molar mass 162.24g/mol, what's the molecular formula? 3) A 50.0 g sample of the hydrate of barium hydroxide contains 27.2 g of Ba(OH)2, what's the value of X in Ba(OH)2 . XH2O