Which of the following is an example of a chemical change?

Correct option is A

S. Ans. (a)

Sol.
The correct answer is Burning wood, as it is an example of a chemical change. In a chemical change, the composition of the substance changes, and new substances are formed. When wood burns, it reacts with oxygen in the air to form new substances such as carbon dioxide, water vapor, and ash. This is a chemical reaction, and the original substance (wood) is altered at the molecular level.

Information Booster:

1. Chemical changes often involve the release or absorption of energy in the form of heat, light, or sound.
2. Burning involves a combustion reaction where oxygen reacts with a fuel to produce heat and new products.
3. Chemical changes are usually irreversible; once wood has burned, it cannot be turned back into its original form.
4. Common examples of chemical changes include rusting of iron, baking a cake, and digestion of food.
5. In chemical changes, the atoms rearrange to form different molecules, unlike in physical changes, where the molecules remain the same.
6. The formation of a precipitate or a color change can also indicate a chemical change.

Additional Information:

• The incorrect options:
• (b) Cutting paper: Cutting is a physical change because the paper’s composition remains unchanged.
• (c) Boiling water: Boiling is a physical change because water is still H₂O, and only its state (from liquid to gas) changes.
• (d) Melting ice: Melting is also a physical change where only the state of matter changes from solid to liquid.