Question

Indicate the number of `sigma` and `pi` bonds in the following molecules:
(i) `CH_(3)-CH=CH_(2)` (ii) `CH_(3)-CH_(2)-CH_(2)-CH_(3)`
(iii) `CH_(3)-C-=C-CH_(3)` (iv)

Answer 1

For finding out the number of `sigma`-and `pi`-bonds in a molecule, the following points should be kept in mind:
1. All single bonds are sigma bonds.
2. All double bonds consists of one `sigma`-and one `pi-`bonds.
3. All triple bonds consist of one `sigma`-and two `pi-`bonds.
(i) This molecule consists of even single bonds and one double bond. Thus, number of `sigma`-bonds = 8 and number of `pi`-bond = 1.
(ii) This molecule consists of 13 single bonds. Thus, number of `sigma`-bonds = 13.
(iii) This molecule consists of 8 single bonds and one triple bond. Thus, number of `sigma`-bonds = 9 and number of `pi`-bonds = 2.
(iv) The molecule of benzene consists of nine single bonds and three double bonds.
Thus, number of `sigma`-bonds = 12 and number of `pi`-bonds = 3.