Question

What is the number of sigma and pi bonds in `CH_3CN`?

Answer 1

`6 sigma + 2 pi`

Explanation:

In the methyl `CH_3` group, there are `3` `sigma`-bonds between the carbon and hydrogen, because you can't double bond a hydrogen so there are no `pi`'s.

Now that carbon has `3` bonds of its total `4`, so there is only one left to bond to the second carbon. That gives another `sigma`-bond, making `4sigma` in total so far.

The second carbon has only one bond at the moment, so to be stable it must have `3` more bonds with the nitrogen to fill all of their outer shells. If there is a triple bond, there must be one `sigma` and two `pi` bonds.

In total, there are `6 sigma + 2 pi` bonds.