How do you actually know the chemical formulae for the ionic compound

Does anyone know a lot about how to: - calculate mass of magnesium metal - calculate the actual yield of magnesium oxide - calculate the theoretical yield of mgo - calculate the percent yield of mgo - determine the percent yield of mgo - determine the average percent yield of mgo i had to do an online lab and its asking these questions but i have no idea where to start or how to be able to find these things. i can post the chart of the data from the lab or if you can tell me exactly how i can find each.

6. what does the symbol ah stand for? o one calorie given off by a reaction the specific heat of a substance the heat capacity of a substance the heat of reaction for a chemical reaction

Which element is the least metallic between cadmium, silver, zinc, or iron?