A student scratches a rock sample with his fingernail and leaves marks on the rock. What can be determined about this rock?

Question

A.The rock is six centimeters across.
B.The rock is oval like an egg.
C.The rock is grey with a white stripe.
D.The rock has many pores.

Answer 1

The answer is none of the above. Scratching the rock sample with a fingernail reveals the physical property of hardness of the rock. If the rock is soft enough to be scratched with a fingernail, it means that the rock is relatively "soft" or "less hard" compared to other minerals or rocks with a higher level of hardness, like quartz or diamond. Therefore, it can be determined that the rock is not a hard mineral like quartz, topaz, or diamond, etc.