Sodium oxide is a simple strongly basic oxide. It is basic because it contains the oxide ion, O2-, which is a very strong base with a high tendency to combine with hydrogen ions. Reaction with water: Sodium oxide reacts exothermically with cold water to produce sodium hydroxide solution
When you line the object up against the ruler you are measuring it's side, if you put it on the one instead of the zero then you're making the object one inch longer, so you'd have to subtract the one in the end
