A substance which reacts with oxygen giving heat is called a combustible substance. Which, one of the following is a combustible substance?

Options

A. iron nail
B. glass
C. stone piece
D. wood

Answer

**Step-by-Step Solution:**

1. **Understanding Combustible Substances**: A combustible substance is defined as a material that reacts with oxygen and produces heat when it burns. This process is known as combustion.

2. **Identifying Options**: The question presents four options, and we need to determine which one is a combustible substance.

3. **Analyzing Each Option**:
- **Wood**: Wood is a natural fiber that reacts with oxygen when burned, producing heat and light. Therefore, it is a combustible substance.
- **Iron Nail**: An iron nail can rust when exposed to air, which is a different chemical reaction (corrosion) and does not produce heat in the same way combustion does. Thus, it is not a combustible substance.
- **Glass**: Glass does not react with oxygen and does not burn, so it is not a combustible substance.
- **Stone**: Similar to glass, stone does not undergo combustion and does not react with oxygen in a way that produces heat.

4. **Conclusion**: Among the options provided, wood is the only substance that fits the definition of a combustible substance.

5. **Final Answer**: Wood is the correct answer as it is a combustible substance.

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