Question

question 4 what is the primary purpose of using common objects in mineral hardness testing? to test only metallic minerals to replace the mohs scale entirely to get more accurate results to provide convenient testing alternatives

Explanation:

Common objects like fingernails, copper coins, glass are easily - accessible. They are used in mineral hardness testing to offer a convenient way to estimate a mineral's hardness without needing specialized equipment. Moh's scale is still widely used, and common - object testing doesn't replace it. Results from common objects are not necessarily more accurate than Moh's scale, and it's not limited to metallic minerals.

Answer:

To provide convenient testing alternatives