When two A.O. combine they form B.MO & ABMO. During BMO .x. energy is released & during ABMO .y. energy is absorbed. So the correct relation will be :-

Options

A. x = y
B. `x lt y`
C. `y lt x`
D. None of these

Answer

To solve the problem, we need to analyze the energy changes that occur when two atomic orbitals (A.O.) combine to form bonding molecular orbitals (B.M.O.) and anti-bonding molecular orbitals (A.B.M.O.).

### Step-by-Step Solution:

1. **Understanding Atomic Orbitals (A.O.)**:
- When two atomic orbitals combine, they can form two types of molecular orbitals: bonding molecular orbitals (B.M.O.) and anti-bonding molecular orbitals (A.B.M.O.).
- For example, consider two 1s atomic orbitals combining.

2. **Formation of Bonding and Anti-bonding Orbitals**:
- The combination of two atomic orbitals results in one bonding molecular orbital (B.M.O.) and one anti-bonding molecular orbital (A.B.M.O.).
- The bonding molecular orbital is lower in energy compared to the original atomic orbitals, while the anti-bonding molecular orbital is higher in energy.

3. **Energy Changes During Formation**:
- When the bonding molecular orbital is formed, energy (let's denote this as x) is released. This is because the system moves to a lower energy state.
- Conversely, when the anti-bonding molecular orbital is formed, energy (denote this as y) is absorbed. This is because the system moves to a higher energy state.

4. **Applying the Law of Conservation of Energy**:
- According to the law of conservation of energy, the energy released during the formation of the bonding molecular orbital must equal the energy absorbed during the formation of the anti-bonding molecular orbital.
- Therefore, we can establish the relationship: \( x = y \).

5. **Conclusion**:
- The correct relation between the energies x and y is that they are equal, i.e., \( x = y \).

### Final Answer:
The correct relation is \( x = y \).

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