please aswer the following?

Question

how would would the following affect the Mg/O ration in an experiment: would the ratio become larger or smaller than the true value? and why:

1.If not all the magnesium burned?
2. if not all the excess water aded was boiled away?

Answer 1

If the Mg didn't all burn, the final weight would be lighter than it should be and it would make it appear as if less oxygen combined with the Mg than would have actually been the case.

If there was water remaining in the sample the weight would be more than it should be, and it would make it appear as if more oxygen had reacted with the Mg than was actually the case.