Question

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

Answer 1

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.

Answer 2

• magnesium is a very reactive metal.
• it reacts with oxygen to form a layer  magnesium oxide on its surface.
• it prevents further reaction of Mg of O2

thus, Mg ribbon must be cleaned to get rid of this outer layer.