Question

${{N}_{2}}$ is less reactive than $C{{N}^{-}}$ due to
(A) Presence of more electrons in orbital
(B) Absence of dipole moment
(C) Difference in spin quantum number
(D) None of these

Answer 1

Hint: A nitrogen molecule (${{N}_{2}}$) contains two nitrogen atoms where each nitrogen is sp hybridised. A cyanide ion ($C{{N}^{-}}$) contains one carbon and one nitrogen atom. Both molecules have a triple bond between the two atoms.

Complete Step by Step Answer:
The nitrogen molecule is nonpolar due to the presence of the same atoms forming the bond. It does not possess a dipole moment. While the cyanide ion is polar as it contains two atoms with some electronegativity difference. Hence, it has a dipole moment. This is the reason $C{{N}^{-}}$ is more reactive.

The nitrogen molecule is a highly stable compound due to the presence of a triple bond and is therefore less reactive. Hence, ${{N}_{2}}$ is less reactive than $C{{N}^{-}}$ due to the absence of a dipole moment in it.
Correct Option: (B) Absence of dipole moment.

Additional Information: A dipole moment is a measure of the electronegativity difference between the two atoms of a bond. The electronegativity difference means that one of the atoms in the bond can attract the shared pair of electrons more strongly than the other. Both the ionic and covalent bond can possess a dipole moment. It is a vector quantity and thus possesses both magnitude and direction.

Note: Both the nitrogen molecule and the cyanide have the same number of electrons and their spin quantum numbers are also the same.