Plant and animal matter on burning produces mainly-
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Carbon dioxide
Plant and animal matter is made mostly of compounds of carbon (with hydrogen and oxygen), such as cellulose, starch, proteins and fats. On burning, these combine with oxygen of the air, and the carbon is given out mainly as carbon dioxide, along with water vapour and heat.
Why the other options are incorrect
Option (2) Oxygen — Incorrect. Oxygen is used up in burning, not produced by it.
Option (3) Nitrogen — Incorrect. Nitrogen is present only in small amounts in proteins, so it is not the main product.
Option (4) Methane — Incorrect. Methane is produced when such matter decays without air, as in marshes and biogas plants, not when it burns.