Which scale is used to measure the hardness of materials?

The Mohs Scale is the correct choice for measuring the hardness of materials because it quantifies how easily one mineral can scratch another. Developed by Friedrich Mohs in 1812, the scale ranks minerals on a scale from 1 to 10, with talc as the softest mineral (1) and diamond as the hardest (10). Each mineral in the scale can scratch those below it and can be scratched by those above it, providing a comparative measure of hardness. This simple and effective method is widely used in geology and mineralogy to identify minerals based on their physical properties.

The other options do not serve the purpose of measuring hardness. The temperature scale measures thermal energy, the Rock Scale is not a recognized standard in hardness measurement, and the density scale assesses mass per unit volume, which does not correlate with hardness. Therefore, the Mohs Scale is specifically designed and recognized for evaluating the hardness of materials.