a solution. a mixture. a compound. an element.
I gave my students this multiple choice question: When magnesium (Mg) metal is burned in the presence of oxygen (O?), magnesium oxide (MgO) is produced. The properties of magnesium oxide are different than the individual properties of magnesium and oxygen because magnesium oxide is

Only one answer is correct among these 4 choices:
- a solution.
- a mixture.
- a compound.
- an element.

Could you tell me which one is correct?

a compound.