Question

magnesium metal, a gray solid, is heated in a crucible in the presence of oxygen. a white powder is collected from the crucible. this is an example of answer: a chemical change a separation a mixture a physical change

Explanation:

When magnesium metal reacts with oxygen, a new substance (magnesium oxide) is formed. This is characteristic of a chemical change. In a chemical change, new substances with different properties are created. A physical change would not result in a new substance. A mixture is a combination of substances without a chemical reaction. Separation refers to isolating components, which is not the case here.

Answer:

A. a chemical change