The burning of the magnesium becomes uncontrolled (it burns brightly). Oops! Will the reported mole ratio of magnesium to oxygen be too high or too low as a result of this technique error?

Answer

Mole ratio of magnesium to Oxygen will be too low.

Explanation:

When magnesium burns in air, it reacts with oxygen vigorously to form an ionic compound,MgO with a flame that is a brilliantly white. Normally, stability of an atom depends on whether their outermost shell contains maximum electrons. Durning combination with Oxygen, Magnesium tends to give two of its electron causing it to be stable because it has a full outermost shell. It forms Mg+2 ion, Oxygen, on the other hand gains the two electrons, which fills its outermost most shell. It also now has more electrons than protons

The MOLE RATIO of magnesium to oxygen would be too low, because there will be MORE oxygen present than there should have been.