Question

How many sigma and pi bonds are in the molecule ch3chch2? 1. 6 sigma and 2 pi 2. 2 sigma and 1 pi 3. 9 sigma and 0 pi 4. 8 sigma and 1 pi 5. 7 sigma and 2 pi 6. 7 sigma and 1 pi?

Answer 1

The molecule is as follows;
H₃C---C==CH₂
           |
         H
--- represents single bonds whilst == represents double bonds
Single bonds are formed by sigma orbital head on overlap between sigma orbitals of C and H in the case of C-H bonds and between C sigma orbitals in the case of C-C bonds 
the number of sigma bonds are therefore the number of single bonds which are:
6 C-H bonds
2 C-C bonds
altogether 8 sigma bonds 
p orbitals side- on overlap forms a pi bond. In double bonds, there's one sigma bond and one pi bond.
number of double bonds - 1 C=C therefore one pi bond 
Answer is 4) 8 sigma and 1 pi