According to MOT, two atomic orbitals overlap resulting in the formation of molecular orbital formed. Number of atomic orbitals overlapping together is equal to the molecule orbital formed. The two atomic orbital thus formed by LCAO (linear combination of atomic orbital) in the phase or in the different phase are known as bonding and antibonding molecular orbitals respectively. The energy of bonding molecular orbital is lower than that of the pure atomic orbitals by an amount `Delta`. This known as the stabilization energy. The enerby of antibonding molecular orbital in increased by `Delta'` (destabilisation energy).
Q. which of the following combination of orbitals is corrects?

Options

A.
B.
C.
D.

Explanation

To solve the question regarding the correct combinations of atomic orbitals that form molecular orbitals according to Molecular Orbital Theory (MOT), we will analyze the combinations provided in the question step by step.

### Step 1: Understanding the Concept of Molecular Orbitals
Molecular Orbital Theory states that when two atomic orbitals overlap, they form molecular orbitals. The number of molecular orbitals formed is equal to the number of atomic orbitals that combine. There are two types of molecular orbitals:
- **Bonding Molecular Orbitals**: Formed when atomic orbitals combine in phase (constructively), resulting in lower energy.
- **Antibonding Molecular Orbitals**: Formed when atomic orbitals combine out of phase (destructively), resulting in higher energy.

### Step 2: Analyzing the Given Combinations
We need to evaluate the combinations of atomic orbitals provided in the question to determine which one is correct.

1. **Combination of Two 2p Orbitals**:
- When two 2p orbitals overlap, they can form bonding and antibonding molecular orbitals. If they overlap in phase, they create a bonding molecular orbital, and if they overlap out of phase, they create an antibonding molecular orbital. This combination is valid.

2. **Combination of One S Orbital and One P Orbital**:
- An S orbital can combine with a P orbital to form molecular orbitals, but the resulting molecular orbitals will not be purely bonding or antibonding in the same manner as two orbitals of the same type. This combination is generally valid but may not lead to a simple bonding/antibonding distinction as seen with two identical orbitals.

3. **Combination of Two Orbitals Arranged on the Y-Axis**:
- If two orbitals are arranged on the y-axis, they can form a pi bond if they are p orbitals. However, if they are not aligned properly, the overlap may not lead to effective bonding. This combination may not be valid for forming stable molecular orbitals.

### Step 3: Conclusion
Based on the analysis:
- The combination of two 2p orbitals is the only one that consistently leads to the formation of bonding and antibonding molecular orbitals in a straightforward manner.

Therefore, the correct answer is the combination of **two 2p orbitals**.