A combustible substance can catch fire on its own.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Statement**: The statement claims that a combustible substance can catch fire on its own. We need to analyze this statement to determine its truthfulness.

2. **Definition of Combustible Substance**: A combustible substance is any material that can burn in the presence of oxygen. However, just being combustible does not mean it will catch fire spontaneously.

3. **Introduction to Ignition Temperature**: Every combustible substance has a specific temperature known as the ignition temperature. This is the minimum temperature required for the substance to ignite and start burning.

4. **Role of Ignition Temperature**: If the temperature of the combustible substance is below its ignition temperature, it will not catch fire, even if it is in the presence of oxygen. Therefore, a combustible substance cannot catch fire on its own unless it reaches this ignition temperature.

5. **Conclusion**: Since a combustible substance cannot ignite without reaching its ignition temperature, the original statement is false.

**Final Answer**: A combustible substance cannot catch fire on its own; it requires a certain temperature (ignition temperature) to ignite.

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