Final answer:
The H2C=C=CH2 molecule contains nine sigma bonds and two pi bonds, with sigma bonds including single bonds and one component of double bonds, and pi bonds forming the second component of double bonds.
Step-by-step explanation:
In the molecule H2C=C=CH2, there are several types of bonds that hold the atoms together. Specifically, the molecule contains sigma (σ) and pi (π) bonds. A σ bond is a type of covalent bond where the electron density is concentrated between the nuclei of the bonding atoms, resulting from head-on overlapping of orbitals. The sp² hybrid orbitals form these σ bonds. On the other hand, a π bond is formed from the side-by-side overlap of p orbitals, where the electron density is concentrated above and below the nuclei of the bonding atoms.
For H2C=C=CH2, there are a total of nine σ bonds and two π bonds. These include six C-H σ bonds and one σ bond between carbons as part of the underlying single bonds, and each double bond consists of one σ bond and one π bond. Since there are two double bonds in the molecule, we get a total of two π bonds in the molecule.