Which of these is a physical property of wood? a. wood can burn. b. wood can rot. c. wood does not rust. d. wood is softer than coal.

Wood being softer than coal is a physical property. Any chemical property has to deal with a change in somethings composition. When would is burnt, rotted, or not rusted, it is because there is some form of chemical reaction (Or lack thereof) inside of the wood. The property of being softer, however, does not come about by changing what wood is.