Thermal Decomposition or Pyrolysis or Cracking.

Explanation

**Step-by-Step Text Solution:**

1. **Definition of Thermal Decomposition (Pyrolysis or Cracking):**
- Thermal decomposition, also known as pyrolysis or cracking, is a chemical process where organic compounds, particularly hydrocarbons, are broken down into smaller molecules when subjected to high temperatures (approximately 770 to 870 Kelvin).

2. **Understanding the Process:**
- In this process, larger alkane molecules decompose into smaller alkane and alkene molecules. The breaking of carbon-carbon bonds occurs due to the application of heat, leading to the formation of various products.

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