Final answer:
The total number of sigma bonds in the given molecules is twelve, with nine sigma bonds from butadiene and three sigma bonds from acetylene.
Step-by-step explanation:
The total number of sigma (σ) bonds in the compound CH3-CH=CH2 + C≡CH2 is determined by analyzing each type of bond in the molecule. In the molecule butadiene (C4H6), there are single bonds, which are sigma bonds, and double bonds, which have both a sigma and a pi (π) bond.
Counting only the sigma bonds, there are six C-H sigma bonds and one C-C sigma bond from the single bonds. In addition, each of the two double bonds also contributes one sigma bond. Therefore, the total number of sigma bonds in butadiene is nine (6 C-H bonds + 1 C-C single bond + 2 C-C double bond sigma components).
Examining the second molecule C≡CH2 (acetylene), there are two C-H sigma bonds and one C-C triple bond, which contains one sigma bond and two pi bonds. Thus, the total count of sigma bonds here is three (2 C-H bonds + 1 C-C triple bond sigma component).
Adding the sigma bonds from butadiene and acetylene together, the total is twelve sigma bonds (9 from butadiene + 3 from acetylene).