How will the relative number of moles of Mg and O be affected if the following procedural errors are made? Briefly explain

(1) the crubile is not brought to constatn mass before the Mg is added.
(2) water is not added after the first heating of Mg, and the entire solid in the crucible is considered to be magnesium oxide.
(3) some of the fluffy white precipiate is lost before the crucible is weighed for the last time.
(4) In an effort to begin a second while the first is cooling, the hot crucible containing the solid from determination 1 is accidently dropped, and a small chip is lost from the crucible.