JEE MainChemistryChemical Bonding and Molecular Structure
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : In an HNO ₃ molecule, all three N - O bond lengths are identical, similar to the NO ₃^- ion. Reason (R) : Both HNO ₃ and NO ₃^- exhibit symmetric resonance involving all three oxygen atoms equally. In the light of the above statements, choose the most appropriate answer from the options given bel
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- B(A) is correct but (R) is not correct
- CBoth (A) and (R) are not correct
- D(A) is not correct but (R) is correct
Correct answer
C. Both (A) and (R) are not correct
Step-by-step solution
In the nitrate ion ( NO ₃^- ), the negative charge is delocalized equally over all three oxygen atoms due to symmetric resonance. Thus, all three N - O bond lengths are identical (bond order = 1.33 ). In nitric acid ( HNO ₃ ), one of the oxygen atoms is bonded to a hydrogen atom ( N - OH ). This oxygen atom does not participate equally in the resonance delocalization with the other two terminal oxygen atoms. As a result, the N - OH bond is essentially a single bond and is longer, while the other two N - O bonds hav