Question

How do you count pi bonds?

Answer 1

Look at double and triple bonds.

Explanation:

Each double bond is made up of one `pi` bond and one `sigma` bond, and each triple bond is made up of two `pi` bonds and one `sigma` bond (each single bond is made up of just one `sigma` bond).

For example, acetylene has the structure:

It contains one triple bond, so we can conclude that it has two pi bonds.