Which statement about hybridization in the following is not correct ?

Options

A. Hybridization is the mixing of atomic orbitals prior to their combining into molecular orbitals
B. `sp^2` hydbrid orbitals are formed from two p atomic orbitals and one S atomic orbital
C. `d^2sp^3` hybrid orbitals are directed towards the corners of a regular octahedron
D. `sp^3d` hybridd orbitals are all at `90^@` to one another

Answer

To solve the question about which statement regarding hybridization is not correct, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Understanding Hybridization**:
- Hybridization is the process of mixing atomic orbitals to form new hybrid orbitals that are suitable for the pairing of electrons to form chemical bonds in molecular geometry.

2. **Analyzing Statement 1**:
- **Statement**: "Hybridization is the mixing of atomic orbitals prior to combining into molecular orbitals."
- **Evaluation**: This statement is true. Hybridization involves the mixing of atomic orbitals (like s, p, d) to create new hybrid orbitals that participate in bonding.

3. **Analyzing Statement 2**:
- **Statement**: "sp² hybrid orbitals are formed by 2p atomic orbitals and 1s atomic orbital."
- **Evaluation**: This statement is also true. In sp² hybridization, one s orbital and two p orbitals mix to form three equivalent sp² hybrid orbitals.

4. **Analyzing Statement 3**:
- **Statement**: "d²sp³ hybrid orbitals are directed towards the corners of a regular octahedron."
- **Evaluation**: This statement is true. The d²sp³ hybridization leads to an octahedral geometry where the hybrid orbitals point towards the corners of an octahedron.

5. **Analyzing Statement 4**:
- **Statement**: "sp³ hybrid orbitals are all at 90 degrees to one another."
- **Evaluation**: This statement is false. In sp³ hybridization, the four hybrid orbitals are arranged in a tetrahedral geometry with bond angles of approximately 109.5 degrees, not 90 degrees.

6. **Conclusion**:
- The statement that is not correct is Statement 4: "sp³ hybrid orbitals are all at 90 degrees to one another." Therefore, the answer to the question is Statement 4.

### Final Answer:
The statement that is not correct about hybridization is: "sp³ hybrid orbitals are all at 90 degrees to one another."