How many 𝜎 and 𝜋 bonds are in this molecule?

(a) HC≡C−CH=CH−CH
3
​

(b ) CH
2
​
=C=CH−CH
3
​

Solution

(a) HC≡C−CH=CH−CH
3
​

Total pi bond =3π

Total sigma bond =4(C−C)+6(C−H)=10σ

(b ) CH
2
​
=C=CH−CH
3
​

Total pi bond =2π

Total sigma bond =3(C−C)+6(C−H)=9σ