Burning of wood is a chemical change.

Explanation:
A chemical change, also known as a chemical reaction, involves the formation of new substances with different properties. In the case of burning wood, the chemical reactions involved result in the formation of new substances, such as carbon dioxide, water vapor, and ash.

1. Definition of a chemical change:
- A chemical change occurs when the substance undergoes a transformation, resulting in the formation of new substances.
- It is characterized by the breaking and forming of chemical bonds.

2. Burning of wood:
- When wood is burned, it undergoes a chemical change.
- The heat from the fire causes the complex organic molecules present in wood, such as cellulose, lignin, and hemicellulose, to break down through a process called combustion.
- Combustion is a chemical reaction that involves the reaction of a fuel (wood in this case) with oxygen in the air to produce heat, light, and new substances.

3. Chemical reactions during wood burning:
- The main chemical reactions that occur during the burning of wood are oxidation reactions.
- Oxygen from the air combines with the carbon, hydrogen, and other elements present in wood to form carbon dioxide (CO2) and water vapor (H2O).
- The release of heat and light energy is also a result of these chemical reactions.

4. Evidence of a chemical change during wood burning:
- Several observable changes occur during the burning of wood, indicating a chemical change:
a) Production of heat and light: The release of energy in the form of heat and light is a characteristic of chemical reactions.
b) Change in color and odor: The wood turns black and emits smoke, indicating the formation of new substances.
c) Formation of ash: The residue left behind after the wood has burned is ash, which is made up of the non-combustible components of wood.

In conclusion, the burning of wood is a chemical change because it involves the formation of new substances through chemical reactions.