Considering x-axis as the internuclear axis which out of the following will not form a sigma bond and why?

A. 1s and 1s


B. 1s and 2px;


C. 2py and 2py


D. 1s and 2s.

2py and 2py orbitals will not a form a sigma bond. Taking x-axis as the internuclear axis, 2py and 2py orbitals will undergo lateral overlapping, thereby forming a pi bond.


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