Question

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

Answer 1

Answer:

Magnesium ribbon should be cleaned with sandpaper before burning in the air. ... To remove the Magnesium oxide layer from the ribbon which may prevent or slow down the burning of magnesium ribbon. Unwanted impurities deposited on the magnesium ribbon can be removed and only pure magnesium can be used for the reaction.

Answer 2

Magnesium ribbon is cleaned before burning because a layer of magnesium oxide is formed which may slow down burning of magnesium ribbon

Hope it helps