Question

In each of the following pairs, select the species having the greater resonance stabilization.

(i) $HN{O}_3$ and ${N{O}_3}^{-}$ (pair I)
(ii) $H_{2}C=O$ and $HCO{O}^{-}$ (pair II)

• A. $HN{O}_3$ has greater resonance in pair (I)
• B. $N{O}_3^{-}$ has greater resonance in pair (I)
• C. $H_{2}C=O$ has greater resonance in pair (II)
• D. $HCO{O}^{-}$ has greater resonance in pair (II)

Answer 1

Answer: (B), (D)

$N{O}_3^{-}$ has greater resonance in pair (I)
$HCO{O}^{-}$ has greater resonance in pair (II)

Nitrate ion has greater resonance stabilization than nitric acid. In nitric acid, the resonance structures have charge separation, whereas in nitrite ion such charge separation is not present in the resonance
structures.
Hence, the option A is incorrect and the option B is correct.
Formate ion has greater resonance stabilization than formaldehyde. In formaldehyde, the resonance structures will contain charge separation.
Such charge separation is not present in the resonance structures of formate ion.
Hence, the option C is incorrect and the option D is correct.