What is the percent composition by mass of oxygen in magnesium oxide, MgO?
(Molar mass of MgO = 40.3 g/mol)
%
Your answer should be rounded to three significant figures. Do not include units
In your answer.

Some liquids can be distilled, but only at temperatures that are so high that it is impractical, or so high the compound decomposes. explain why distillation such compounds at significantly less than atmospheric pressure (some degree of vacuum) would solve this problem.