Question

How do you find `sp^2` carbons?

Answer 1

A carbon having three `sigma` and one `pi` bond is `sp^2` carbon.
While a carbon having 2 `sigma` and 2 `pi` is `sp` carbon.

eg. `O=C=O` In the molecule of carbon dioxide (`CO_2`) , carbon is having 2 `sigma` and 2 `pi` so the carbon is `sp` hybridised.

eg. in ethene ( `C_2H_4` ) each carbon is having 3 `sigma` and one `pi` , hence `sp^2` hybridised.