Burning of Mg in air is.

Options

A. physical change
B. chemical change
C. sublimation
D. oxidation-reduction

Explanation

### Step-by-Step Solution:

1. **Identify the Reaction**: When magnesium (Mg) burns in air, it reacts with oxygen (O2) to form magnesium oxide (MgO). The chemical equation for this reaction is:
\[ \text{Mg} + \text{O}_2 \rightarrow \text{MgO} \]

2. **Determine the Type of Change**: The burning of magnesium is a combustion reaction. In a combustion reaction, a substance reacts with oxygen, producing heat and light, and results in the formation of new products.

3. **Classify the Change**:
- **Physical Change**: This involves changes that do not alter the chemical composition of a substance. Since burning magnesium produces a new substance (MgO), it is not a physical change.
- **Chemical Change**: This involves a transformation where reactants are converted into products with different properties. The burning of magnesium fits this definition as it produces magnesium oxide, which has different properties than magnesium and oxygen.
- **Sublimation**: This is the process where a solid turns directly into vapor without becoming liquid. This does not apply to the burning of magnesium.
- **Oxidation-Reduction (Redox Reaction)**: While the reaction does involve oxidation (magnesium is oxidized), it is primarily classified as a chemical change due to the formation of a new compound.

4. **Conclusion**: Therefore, the burning of magnesium in air is classified as a **chemical change**.

### Final Answer:
The burning of magnesium in air is a **Chemical Change**.

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