What is a chemical property of a substance a; color
b; reactivity
c; melting point
d; density

A chemical property is a characteristic of a particular substance that can be observed in a chemical reaction. Some major chemical properties include flammability, toxicity, heat of combustion, pH value, rate of radioactive decay, and chemical stability.

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Chemical properties can only be established by changing a substance's chemical identity, and are different from physical properties, which can be observed by viewing or touching a sample. The internal qualities of a substance must be altered to determine its chemical properties.

i believe it would be c: tons.