Introduction:
When considering the compound C2, it is important to understand the concept of s p mixing and its role in determining the properties of molecules. S p mixing refers to the interaction between the s and p atomic orbitals of the same energy level, resulting in the formation of hybrid orbitals. These hybrid orbitals influence the bonding and magnetic properties of molecules.

Effect of s p Mixing:
S p mixing can have a significant impact on the properties of a molecule. When s p mixing is operative, the molecular orbitals formed are non-degenerate, meaning they have different energies. This leads to a splitting of the molecular orbitals into different energy levels, resulting in different bonding and magnetic properties.

C2 Molecule:
In the case of C2, the carbon atoms are connected by a double bond. Each carbon atom has two valence electrons in the 2s orbital and two valence electrons in the 2p orbitals. Without s p mixing, the molecular orbitals in C2 are formed by the overlap of the 2p orbitals.

Bond Order:
The bond order (BO) of a molecule is calculated by subtracting the number of anti-bonding electrons from the number of bonding electrons and dividing the result by 2. A positive bond order indicates a stable molecule, while a bond order of zero or negative indicates an unstable molecule.

BO = 2:
If s p mixing is not operative in C2, the molecular orbitals formed by the overlap of the 2p orbitals will be non-degenerate. This results in two bonding orbitals and two anti-bonding orbitals. The number of bonding electrons is four, and the number of anti-bonding electrons is also four. Therefore, the bond order (BO) is calculated as [(4 - 4) / 2] = 0.

Paramagnetic or Diamagnetic:
A molecule is paramagnetic if it has unpaired electrons and diamagnetic if all the electrons are paired. In the case of C2 with a bond order of 2, there are no unpaired electrons. Each bonding orbital is fully occupied by a pair of electrons, resulting in all the electrons being paired. Therefore, C2 is diamagnetic.

Conclusion:
In conclusion, if s p mixing is not operative in C2, the bond order will be 2, indicating stability. Furthermore, C2 will be diamagnetic since all its electrons are paired. It is crucial to understand the concept of s p mixing and its effect on molecular properties to accurately determine the characteristics of molecules like C2.

BO--2= paramagnetic and BO ---3= diamagnetic