JEE Advanced levelSingle correct optionDifficulty 3 of 3cb047
In nitric acid, HNOX3, the average bond orders of the N-OH bond and of the two other N-O bonds are, respectively,
A1, 1.5 and 1.5
B1, 2 and 2
C1, 1 and 2
D1.5, 1.5 and 1.5
Answer: A
The structure has N-OH single, plus one N=O and one N-O− that interchange by resonance. The two non-hydroxyl N-O bonds each average (2+1)/2=1.5, while N-OH stays 1.