Define oxidation in terms on Oxygen and Hydrogen.

Explanation

### Step-by-Step Solution:

1. **Definition of Oxidation**:
- Oxidation can be defined as a chemical process that involves the addition of oxygen to a substance or the removal of hydrogen from it.

2. **Oxidation in Terms of Oxygen**:
- When a substance gains oxygen, it undergoes oxidation.
- **Example**: Consider the reaction of magnesium with oxygen:
\[ 2 \text{Mg} + \text{O}_2 \rightarrow 2 \text{MgO} \]
In this reaction, magnesium (Mg) reacts with oxygen (O₂) to form magnesium oxide (MgO). Here, magnesium is oxidized as it gains oxygen.

3. **Oxidation in Terms of Hydrogen**:
- Oxidation can also be defined as the removal of hydrogen from a substance.
- **Example**: Consider the reaction of hydrogen sulfide (H₂S) with chlorine (Cl₂):
\[ \text{H}_2\text{S} + \text{Cl}_2 \rightarrow \text{S} + 2 \text{HCl} \]
In this reaction, hydrogen sulfide is converted into sulfur and hydrochloric acid. Here, hydrogen is removed from hydrogen sulfide, indicating that it has been oxidized.

4. **Conclusion**:
- Therefore, oxidation can be defined in two ways: as the addition of oxygen to a substance or as the removal of hydrogen from a substance.