An unknown mineral is scratched by a penny. it must be talc have a mohs hardness of 10 be softer than a diamond have perfect cleavage

The correct answer is It must be softer than a diamond.

Explanation:

One of the ways to determine what type of mineral is being treated is to test its hardness.

By hardness we mean the resistance with which they can be scratched or cut.

There is a scale called the Mohs Hardness Scale which assigns a number from 1 to 10 to each mineral. Being 1 the softest and 10 the hardest. On this scale,a mineral can only be scratched by harder minerals.

Let's give an example: a diamond could easily cut or scratch a glass. However, this would not be the best way to identify it, since any type of mineral that is harder than 5.5 could cut the glass.

So, what corresponds would be to perform this test on another object, such as a penny. A penny has a hardness of 3, while the diamond is ranked 10 hardness. Therefore, it can be scratched by it.