Which one of the following exceeds octet rule ?

Options

A. The incomplete octet of central atom
B. An odd number of electrons on central atom
C. Expanded octed of the central atom
D. All of these

Explanation

To determine which option exceeds the octet rule, we need to analyze each option based on the definition of the octet rule. The octet rule states that atoms tend to form bonds until they are surrounded by eight valence electrons, achieving a noble gas configuration. Let's go through the options step by step.

### Step-by-Step Solution:

1. **Understanding the Octet Rule**:
- The octet rule indicates that atoms tend to have eight electrons in their valence shell. If an atom has more than eight electrons, it is said to exceed the octet rule.

2. **Analyzing the Options**:
- **Option A: Incomplete octet of central atom**:
- An incomplete octet means that the central atom has fewer than eight electrons in its valence shell. Therefore, this option does not exceed the octet rule. **(Incorrect option)**

- **Option B: Odd number of electrons on central atom**:
- An odd number of electrons means that the total number of valence electrons is not a complete pair. For example, if a central atom has seven electrons, it does not exceed the octet rule as it is still less than eight. **(Incorrect option)**

- **Option C: Expanded octet of central atom**:
- An expanded octet means that the central atom has more than eight electrons in its valence shell. This typically occurs in elements from the third period and beyond, which can accommodate more than eight electrons due to available d-orbitals. **(Correct option)**

- **Option D: All of these**:
- Since options A and B do not exceed the octet rule, this option is also incorrect.

3. **Conclusion**:
- The only option that exceeds the octet rule is **Option C: Expanded octet of central atom**.

### Final Answer:
**Option C: Expanded octet of central atom.**