The correct option is (c).
Explanation
Combustion is a chemical process where a substance reacts with oxygen to release heat and light. The formation of a flame during combustion is specifically dependent on the physical state of the fuel; only substances that vaporize during burning produce a flame.
Statement-wise Analysis:
- Statement 1 is Incorrect. A candle burns with a flame because the solid wax melts, rises up the wick, and turns into vapour. It is the combustion of these vapours that generates the flame. If the wax remained in a solid state without vaporizing (like charcoal), it would glow but not produce a flame.
- Statement 2 is Correct. Oxygen is a prerequisite for combustion. If the air supply is interrupted or cut off, the continuous supply of oxygen required to sustain the chemical reaction ceases, causing the flame to extinguish.
- Statement 3 is Correct. A candle flame typically consists of three zones. The innermost zone (dark zone) around the wick contains unburnt wax vapours. Combustion does not occur in this zone due to the lack of oxygen, making it the least hot part of the flame.
Key Takeaway:
A flame is produced only when a substance vaporizes during burning. The candle flame structure includes the innermost zone (unburnt vapours), the middle zone (partial combustion/luminous), and the outer zone (complete combustion/non-luminous).