Question

Which of the following has maximum bond energy?
(A) C=C
(B) C=O
(C) O=O
(D) N=O

Answer 1

Hint: Bond energy (E) is defined as the amount of energy required to break apart a mole of molecules into its component atoms. It is a measure of the strength of a chemical bond. Bond energy is also known as bond enthalpy (H) or simply as bond strength.

Complete answer:
The bond energy depends upon the nature of bonds, electronegativity of atoms forming the bond and the size of atoms.
Bond energy is based on an average of bond dissociation values for species in the gas phase, typically at a temperature of 298 Kelvin. It may be found by measuring or calculating the enthalpy change of breaking a molecule into its component atoms and ions and dividing the value by the number of chemical bonds. For example, the enthalpy change of breaking methane ${C{H}_{4}}$ into a carbon atom and four hydrogen ions, divided by four (the number of C-H) bonds, yields the bond energy.
Bond energy is not the same thing as bond-dissociation energy. Bond energy values are an average of the bond-dissociation energies within a molecule. Breaking subsequent bonds requires a different amount of energy.
The bond energy depends upon the nature of bonds and multiplicity at bonds but here we find all atoms form double bonds so other factors should be considered like electronegativity
difference and size.
The electronegativity chart is as follows:
O $\to$ 3.44
N $\to$ 3.04
C $\to$ 2.55
As we see the electronegativity difference between carbon and oxygen is large hence its bond energy will be large.
But in other options like between C=C, O=O, N=O the multiplicity of bonds is the same but the electronegativity difference between these atoms are lower as compared to C and
O atoms.
Therefore, the maximum bond energy is between C=O.

Hence the correct option is (B).

Note: The double bond between C and C atom is stronger as it is pure covalent bond also. The extent of overlapping is good but the main factor is electronegativity difference between atoms forming bonds.