Here's why:

* Physical properties are characteristics of a substance that can be observed or measured without changing the substance's chemical composition.

* Hardness describes a material's resistance to scratching or indentation.

* Texture refers to the surface feel of a substance, like smooth, rough, or bumpy.

* Color is how a substance appears to the human eye, based on how it reflects light.

Let me know if you'd like to learn more about physical properties!