When a magnesium ribbon is burnt in oxygen, it gets converted to _________.

magnesium oxide

The correct answer is option 4. magnesium oxide.

When a magnesium ribbon is burned in the presence of oxygen, it undergoes a chemical reaction known as combustion. The reaction between magnesium and oxygen results in the formation of magnesium oxide (MgO). Here's the balanced chemical equation for the reaction:

\[ 2 \text{Mg} + \text{O}_2 \rightarrow 2 \text{MgO} \]

Magnesium oxide is commonly formed as white ash on the surface of the magnesium ribbon during the burning process.