Final answer:
The approximate C-C-C bond angle in propane is 109.5° due to the tetrahedral geometry of sp³ hybridized carbon atoms.
Step-by-step explanation:
The approximate C-C-C bond angle in propane is b) 109.5°. In propane, the carbon atoms are sp³ hybridized, resulting in a tetrahedral geometry around each carbon atom. Since propane is not a cycloalkane and does not have the same level of ring strain seen in cyclopropane, cyclobutane, or cyclopentane, its bond angles resemble the ideal tetrahedral angle. Thus, the C-C-C bond angle is close to the ideal tetrahedral angle of 109.5°, which is characteristic of sp³ hybridized carbon atoms that are not in a ring structure.