The contribution of an electron pair is made by one atom and both the electrons are shared equally by the two atoms to form:
Covalent bond
Chemical bond
Co-ordinate bond
None
As we have learnt, a coordinate bond (also called a dative covalent bond) is a covalent bond in which both electrons come from the same atom.
From the above diagram, it is been seen that in the formation of a complex, both electrons are coming from nitrogen only.
Hence, option number (3) is correct
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