The correct option is (c).
Explanation
Changes in matter are broadly classified into physical and chemical changes. A physical change affects only the physical properties (such as state, shape, or size) without altering the chemical composition. A chemical change involves a chemical reaction resulting in the formation of new substances with different chemical properties, and such changes are typically irreversible.
Statement-wise Analysis:
- Statement 1 is Correct: The burning of wood is a combustion reaction. During this process, the organic compounds in wood (primarily cellulose and lignin) react with oxygen to produce entirely new substances, including carbon dioxide, water vapour, ash, and smoke.
- Statement 2 is Incorrect: Because the process involves a change in chemical composition and the formation of new substances, it is defined as a chemical change. A physical change would imply that the wood remains chemically the same, which is not the case here.
- Statement 3 is Correct: The burning of wood is an irreversible process. Once the wood has been converted into ash and gaseous byproducts, it is impossible to reverse the reaction to recover the original wood.
Key Takeaway:
Combustion (burning) is a chemical change characterized by the formation of new substances (ash, gases) and the release of energy, distinguishing it from physical changes which are reversible and do not alter chemical identity.