Combustion is a chemical process and brings about a chemical change in the substance, i.e., the chemical properties of the substance change upon combustion. Read the questions below and try to answer them.
We do not see things such as cotton clothes and wooden pencils catching fire on their own. Why is this so?

Explanation

### Step-by-Step Solution:

1. **Understanding Combustion**: Combustion is a chemical process that occurs when a substance reacts with oxygen, producing heat and light. For combustion to take place, certain conditions must be met.

2. **Ignition Temperature**: Every material has a specific temperature at which it will ignite and start burning. This is known as the ignition temperature. Cotton and wood have relatively high ignition temperatures.

3. **Presence of Heat**: For cotton clothes and wooden pencils to catch fire, they need to be exposed to a heat source that raises their temperature to the ignition point. In normal conditions, they do not have enough heat to reach this temperature.

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