When magnesium strips are burned in air, is the change observed a physical change or a chemical change?

• A. Neither physical nor chemical change
• B. Chemical change
• C. Physical change
• D. Both physical and chemical change

Answer: (B)

Verified step by step guidance

1. Understand the definitions: A physical change affects the form of a substance but not its chemical composition, while a chemical change results in the formation of one or more new substances with different properties.
2. Consider what happens when magnesium strips burn in air: magnesium reacts with oxygen to form magnesium oxide, a new compound.
3. Recognize that this reaction involves breaking and forming chemical bonds, which means the original substances (magnesium and oxygen) are transformed into a different substance (magnesium oxide).
4. Since a new substance is formed and the chemical composition changes, this process is classified as a chemical change.
5. Therefore, the change observed when magnesium strips burn in air is a chemical change, not a physical change.