The ______ scale is a scale that measures the hardness of a substance

Correct answer: C. Mohs.
The Mohs scale is a scale used to measure the relative hardness of minerals, rocks, and other substances. It was developed by German mineralogist Friedrich Mohs in 1812 and is based on the ability of one material to scratch another. The scale consists of ten minerals, each of which is assigned a ranking from 1 to 10, with 1 being the softest and 10 being the hardest.

Here's how the Mohs scale works:

A material with a higher Mohs hardness number can scratch a material with a lower number.
Conversely, a material with a lower Mohs hardness number cannot scratch a material with a higher number.
For example, diamond, the hardest known naturally occurring substance, has a Mohs hardness of 10 and can scratch any other material on the scale. Talc, on the other hand, has a Mohs hardness of 1 and can be easily scratched by materials with higher hardness ratings.
The Mohs scale is widely used in geology, mineralogy, archaeology, and materials science to help identify and classify minerals and materials based on their hardness properties. It provides a simple and practical way to compare the hardness of different substances and is particularly useful in fields where the physical properties of materials are important.