Question

Why should a magnesium ribbon be cleaned before burning in air?

Answer 1

The magnesium ribbon should be cleaned before burning in the air because the layer of magnesium oxide (which is formed due to the reaction of magnesium with air ) can be removed in order to get the desired chemical reaction.

Also in order to remove the oxide layer, the presence of which slowdowns the oxidation process. So, by cleaning it, the burning process takes place easily.