Now consider methyl cyclopentane. Thus, methyl cyclopentane will have a small dipole moment. Yes, I will be here for the problem session. We need this since there is a test the following Wednesday. Please see response to a previous question.
Propane has a slight dipole moment because it is bent.
Methyl cyclopentane has a dipole moment as well because the substituted methyl group intoduces an asymmetry into the molecule. You really have to look at the structure of the molecule and its symmetry. Don't look for simple rules. This case includes all alkanes, but also CH3Cl. Whenever a carbon atom is boned to 3 atoms, it will be forced to make a double bond with one of them, so that its hybridization will be sp2.