Chemical properties deal with how the substance will behave when brought into contact with other substances, and usually have to do with it undergoing some kind of reaction. Flammability is a chemical property.
Density, melting point, and color are all considered physical properties.
B An enclosed pendulum is not acted on by air resistence or gravity. Plus, pendulum's in clocks are electronic (I think) so that's why it keeps moving back in forth. (at least i think so)