In benzene each carbon is bonded with other carbon and hydrogen. Therefore each carbon there Will be two sigma bonds, one with other carbon and another one is with hydrogen. Now we can calculate no of sigma bonds and pi bonds. There are six carbons so no of sigma bonds 6×2= 12.
When we come to no.of pi bonds in each carbon in benzene there will be one unhybridized orbital that will overlap with other carbon axially to form pi bonds. Each two carbons will overlap axially to form pi bond. There Will be six carbons in benzene so,6÷2=3.Hence, we can say there are 3pi bonds are there in benzene.