Give the stability of the following resonance structures
(a) `H_(2)C = overset(o+)N =overset(Θ)`
(b) `H_(2)overset(o+)C -N =overset(Θ)N`
(c ) `H_(2)overset(Θ)C -overset(o+)N -= N`
(d) `H_(2) overset(Θ)C - N = overset(o+)N` .

Explanation

The lesser the charge separation the more stabel the resonating structure Structures (I) and (III) have less charge separation But in (III) charge is on electropositive `C` atom Therefore (I) is more stable than (III) Since both have six covalent bonds so (I) is more stable than (III) (IgtIII)
(b) Both structures (II) and (IV) have five covalent bonds but (II) is more stable than (IV) becuse in (II) positive charge is on electropositive `C` atom and negative charge is on `EAN` (electonegative) `n` atom whereas in (IV) it is reversed Therefore `IIgtIV` So, the stability order is `I gt III gt II gt IV` .