Question

lab questions! please help!
my data:
mass of empty crucible cover: 29.9g
mass of crucible & cover + Mg: 30.1g
mass of crucible & cover + oxide: 30.2g
mass of magnesium used: 0.2
mass of oxygen that reacted: 0.1
number of moles of Mg: 0.0083
number of moles of O: 0.00625

questions:
1. write the empirical formula of the oxide of magnesium based on your calculations?
2. what is the ratio of the mass in grams of magnesium used to the mass in grams of oxygen that reacted? relate this ratio to the law of definite proportions.