Question

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

Answer 1

Hey buddy here is your answer

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

Hope will help you

Answer 2

A magnesium ribbon is cleaned to remove the protective layer of magnesium oxide from its surface so that it may readily combine with the oxygen of air(on heating).