Final answer:
The item that describes a chemical property is propane's ability to ignite and heat a grill, as it involves a substance undergoing a chemical change into different substances.
Step-by-step explanation:
The item that describes a chemical property is the fact that propane ignites to heat a grill. A chemical property pertains to a substance's ability to change into a different substance, generally through a chemical reaction. For example, combustibility is a chemical property because when a substance burns, it reacts with oxygen, often producing heat and light, and forms new substances.
Comparatively, the other items listed represent physical properties. The viscosity of maple syrup, the dyeing of cotton, and the dissolution of salt in water are all physical changes. These changes do not alter the substances into something new; they simply reflect physical attributes or result in mixtures that retain the individual properties of their components.