Burning of magnesium ribbon is a highly exothermic reaction and so much heat is generated that the ribbon gives off UV rays during the reaction. So, the observations which are made during the burning of magnesium ribbon is as follows:

1. Emission of UV rays from the burning ribbon which is harmful for the human eyes.

2. Emission of large amount of heat during the reaction

3. Burning of magnesium leads to the formation of magnesium oxide as the product.