Give two examples of each : Primary fuel

Explanation

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

1. **Definition of Primary Fuel**:
- Primary fuels are natural resources that can be found in nature and can be extracted, captured, cleaned, or graded without undergoing any energy conversion or transformation process.

2. **Characteristics of Primary Fuels**:
- They are available in their natural state.
- They do not require any significant processing or transformation to be used as fuel.
...