Combination of phosphorus and oxygen is an example of

Options

A. oxidation
B. reduction
C. rancidity
D. none of these

Explanation

To determine what type of reaction occurs when phosphorus combines with oxygen, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**: The reactants in this reaction are phosphorus (P) and oxygen (O2).

2. **Write the Chemical Reaction**: When phosphorus reacts with oxygen, it can form different oxides. The most common reactions are:
- 4P + 3O2 → 2P2O3 (phosphorus trioxide)
- 4P + 5O2 → 2P2O5 (phosphorus pentoxide)

3. **Determine the Type of Reaction**: In both reactions, phosphorus is combining with oxygen. This is a combination reaction where two or more reactants combine to form a single product.

4. **Identify the Process of Oxidation**: In this reaction, phosphorus is gaining oxygen. The addition of oxygen to a substance is defined as oxidation.

5. **Analyze the Options**:
- **Option A (Oxidation)**: Correct, as phosphorus is gaining oxygen.
- **Option B (Reduction)**: Incorrect, as reduction involves the loss of oxygen.
- **Option C (Rancidity)**: Incorrect, as rancidity refers to the oxidation of fats and oils, not the reaction of phosphorus with oxygen.
- **Option D (None of these)**: Incorrect, as oxidation is indeed the correct answer.

6. **Conclusion**: The combination of phosphorus and oxygen is an example of oxidation.

### Final Answer:
The combination of phosphorus and oxygen is an example of **oxidation**.