Formation of Molecular Orbitals

When two atomic orbitals combine, they form molecular orbitals. These molecular orbitals can be classified into two types: bonding orbitals and antibonding orbitals. The combination of two atomic orbitals results in the formation of two molecular orbitals, namely one bonding orbital and one non-bonding orbital.

Bonding Orbital
A bonding orbital is formed when the phase of the two atomic orbitals is the same, resulting in constructive interference. In this case, the electron density between the two nuclei increases, leading to a stable molecular orbital. The bonding orbital is lower in energy compared to the original atomic orbitals.

Non-bonding Orbital
A non-bonding orbital is formed when the phase of the two atomic orbitals is opposite, resulting in destructive interference. In this case, the electron density between the two nuclei decreases, leading to an unstable molecular orbital. The non-bonding orbital is higher in energy compared to the original atomic orbitals.

Explanation of Answer
The correct answer, option 'A', states that the combination of two atomic orbitals results in the formation of one bonding orbital and one non-bonding orbital. This is consistent with the principles of molecular orbital theory.

When two atomic orbitals combine, they can either form a bonding orbital or an antibonding orbital. The bonding orbital is lower in energy and stabilizes the molecule, while the antibonding orbital is higher in energy and makes the molecule less stable.

In the given question, it is stated that the combination of two atomic orbitals results in the formation of two molecular orbitals. This indicates that one of the molecular orbitals formed is a bonding orbital, which stabilizes the molecule. The other molecular orbital formed is a non-bonding orbital, which is higher in energy and does not contribute to the stability of the molecule.

Therefore, the correct answer, option 'A', is one bonding and one non-bonding orbital, as it aligns with the principles of molecular orbital theory.