Question

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

Answer 1

Answer:

Because it forms a layer of MgO by reacting with oxygen present in air which can lead to misoperation in the experiment.

Hope it helps....

Answer 2

$<i> Magnesium is a very reactive metal. When stored, it reacts with oxygen to form a layer of magnesium oxide on its surface. This layer of magnesium oxide is quite stable and prevents further reaction of magnesium with oxygen. The magnesium ribbon is cleaned by sand paper for removing this layer so that the underlying metal can be exposed to air.$