# VidyaSetu · Class 8 Science · Combustion and Flame
## Slides — Combustion Basics (Faculty: Ms. Anita Sharma)

### 1. What is combustion?
A substance reacts with oxygen to give off **heat and light**.
- Products: oxides + heat (+ light)
- Fast chemical reaction

### 2. The fire triangle
Combustion needs all three:
1. **Fuel** — combustible substance
2. **Air** — oxygen supply
3. **Heat** — to reach the *ignition temperature*

### 3. Ignition temperature
Minimum temperature at which a substance catches fire.
- Paper ≈ 130°C · Kerosene ≈ 250°C · Wood ≈ 250–300°C
- Lower ignition temperature → easier to burn

### 4. Types of combustion
| Type | Feature | Example |
|---|---|---|
| Slow | no flame, gradual | respiration |
| Rapid | fast with flame | matchstick |
| Spontaneous | without heating | white phosphorus |
| Smouldering | restricted air | glowing coal |

### 5. Oxides
- Non-metals burn → **acidic oxides** (CO₂, SO₂)
- Metals burn → **basic oxides** (Na₂O, FeO)

### 6. Quick check
1. Define ignition temperature.  2. Why does a matchstick burn easily?
3. Name the cleanest fuel and explain why.