Question

can a copper coin be scratched by .a, your fingernail , b a knife blade? why?
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Answer 1

Answer:

Nope, copper can't be scratched by a fingernail

Answer 2

The Mohs Hardness Scale ranks the order of hardness of minerals and some common objects. For example, your fingernail can scratch the minerals talc and gypsum, with a hardness of 2 or lower. A copper penny can scratch calcite, gypsum, and talc.