Question

The correct stability order of the following resonance structure is:
(I) ${\text{H}}_{\text{2}}\stackrel{-}{\text{C}}-\stackrel{+}{\text{N}}\equiv \text{N}$
(II) ${\text{H}}_{\text{2}}\text{C}=\stackrel{+}{\text{N}}\text{=}\stackrel{-}{\text{N}}$
(III) ${\text{H}}_{\text{2}}\stackrel{+}{\text{C}}-\text{N}=\stackrel{-}{\text{N}}$
(IV) ${\text{H}}_{\text{2}}\stackrel{-}{\text{C}}-\text{N}=\stackrel{+}{\text{N}}$

• A. (I) > (II) > (I) > (III)
• B. (I) > (III) > (II) > (IV)
• C. (II) > (I) > (III) > (IV)
• D. (III) > (I) > (IV) > (II)

Answer 1

The correct option is C (II) > (I) > (III) > (IV)

The stability of resonating structure depends on:

$\bullet$ Maximum covalent bond, more stable.

$\bullet$ Negative charge on more electronegative atom, more stable. Nitrogen is more electronegative than carbon.

$\bullet$ Minimum charge separation, more stable.

$\bullet$ Neutral is more stable than charged.

Hence, the order is $II>I>III>IV$