Why is it important to remove the protective oxide layer from magnesium ribbon before burning it?

Magnesium is a reactive metal and readily reacts with oxygen in the air to form a thin, dull, and stable layer of magnesium oxide (MgO) on its surface. This oxide layer acts as a protective barrier, preventing further reaction of the magnesium with oxygen. If this layer is not removed (e.g., by rubbing with sandpaper) before burning, it will hinder the combustion process, making it difficult for the magnesium to ignite and burn brightly.