Resonance and multicentred bonding

19 questions on Resonance and multicentred bonding from the Chemical Bonding chapter: 3 NEET level, 7 JEE Main, 9 JEE Advanced. Each one opens with its answer and solution.

• The C-O bond order in the carbonate ion, CO3^2-, taking the average over its resonance structures, is NEET level
• Which of the following species cannot be described by resonance structures? NEET level
• Compared with any one of its contributing canonical structures, the resonance hybrid is NEET level
• Which order of C-O bond length is correct? JEE Main level
• In which of the following is each of two carbon-oxygen bonds of exactly the same length because of resonance? JEE Main level
• In the conventional Lewis (dative-bond) description of the dimer Al2Cl6, the number of coordinate (dative) bonds is JEE Main level
• Which statement about canonical (resonance) structures is correct? JEE Main level
• In which of the following species does each bond from the central atom to a terminal O atom have an average bond order of 1.5? JEE Main level
• Naphthalene, C10H8, has two fused six-membered carbon rings. Counting each bond's sigma component once, find the total number of sigma bonds (C-C and C-H) in on... JEE Main level
• The average formal charge on each oxygen atom in the resonance hybrid of CO3^2- is JEE Main level
• In nitric acid, HNO3, the average bond orders of the N-OH bond and of the two other N-O bonds are, respectively, JEE Advanced level
• Diborane, B2H6, has 12 valence electrons in total. The fraction of these electrons that is held in the multicentre (bridging) bonds is JEE Advanced level
• The number of equivalent major (octet-obeying) resonance structures of CO3^2-, NO3-, O3 and NO2- added together is JEE Advanced level
• Assertion (A): All three C-O bonds in CO3^2- have the same length. Reason (R): The carbonate ion rapidly flips among three structures, each with different C-O b... JEE Advanced level
• The thiocyanate ion can be written as (I) S-C#N with a negative charge on S, (II) S=C=N with a negative charge on N and (III) S#C-N. Which of the following stat... JEE Advanced level
• Which statements about diborane, B2H6, are correct? JEE Advanced level
• Which of the following statements about acetate ion and acetic acid are correct? JEE Advanced level
• The numbers of electrons delocalised in the pi system of O3 and of NO3- are, respectively, JEE Advanced level
• The heat of hydrogenation of cyclohexene is -120 kJ mol^-1 and that of benzene is -208 kJ mol^-1. The resonance energy of benzene, in kJ mol^-1, estimated with ... JEE Advanced level