Question

Which of the following statement is not correct for sigma and pi- bonds formed between two carbon atoms ?
A. A sigma bond is stronger tha a pi bond.
B. Bond energies of sigma and pi bonds are of the order of `264kJ mol^(-1)` and `347 kJmol^(-1)`, respectively.
C. Free rotation of atoms about a sigma bond is allowed but not in case of a pi bond.
D. A sigma bond determines the direction between C atoms but a pi bond has no primary effect in this regard.

Answer 1

Correct Answer - B
Since a sigma bond is stronger than a `pi` bond, bond energy of sigma bond must be greater than that of `pi` bond. In fact, the bond energy of `C-Csigma` bond is `347 kJ "mol"^(-1)` while the bond energy of `C-Cpi` bond is `272kJ "mol"^(-1)`.