Question

Why is magnesium ribbon rubbed by sandpaper before burning?

Answer 1

Magnesium ribbon is rubbed by sandpaper before burning so that the layer of magnesium oxide can be removed in order to get the desired chemical reaction.........
Hope my answer will help you.....

Answer 2

With magnesium, the oxide layer forms a white coating on the outside of the metal that will slow down or interfere with the burning process. The ribbons should be sanded with a fine sandpaper, therefore, to remove the layer.