Which of these is a chemical property?
a. boiling point
b. flammability
c. density
d. solubility

Flammability. a chemical property of a substance is the property that can be observed when the substance undergoes a chemical reaction to become a different substance (its molecular composition or arrangement changes e.g methane burns in oxygen to give carbon dioxide and water). since flammability is the ability of a substance to burn, undergoing to process of oxidation, it is a chemical property. boiling point, density and solubility are all physical properties of the substance, i.e. they can be observed without changing the chemical composition (the arrangement or the composition of the molecules of a substance).