How can i justify inserting coefficients from the half reactions

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.

Which element forms an ionic bond with flourine? 1) fluorine 2) carbon 3) potassium 4) oxygen

If two identical atoms are bonded, what kind of molecule is formed