Which property describes the resistance of a material to indentation or scratching?

• A. Ductility
• B. Malleability
• C. Hardness
• D. Toughness

Answer: (C)

Hardness is the property that describes a material’s resistance to surface deformation from indentation or scratching. It focuses on how difficult it is to leave a dent or a scratch on the surface, rather than how much plastic deformation the material can undergo (ductility) or how easily it can be formed (malleability). It’s also different from toughness, which is about how much energy the material can absorb before fracturing. In practice, hardness is measured with tests where an indenter presses into the surface or a scratch is made under a defined load, and the resulting indentation size or scratch depth indicates how hard the material is. Common methods include Rockwell, Brinell, and Vickers indentation tests, as well as the Mohs scratch test. Materials with higher hardness resist indentation and scratching more effectively.