Question

mineral hardness
mohs
hardness scale
talc
gypsum
calcite
fluorite
apatite
feldspar
quartz
topaz
corundum
diamond
approximate
hardness of
common objects
fingernail (2.5)
copper penny (3.5)
iron nail (4.5)
glass (5.5)
steel file (6.5)
streak plate (7.0)
can be scratched by your fingernail
no answers chosen
can scratch a penny, but can not scratch a steel file
no answers chosen
can scratch all other minerals
no answers chosen
possible answers
diamond (10) gypsum (2) fluorite (4) talc (1) feldspar (6) apatite (5)

Explanation:

Can be scratched by your fingernail

Step1: Identify hardness range

A fingernail has a hardness of 2.5. Minerals with a hardness less than 2.5 can be scratched by it.

Step2: Select mineral

Gypsum has a hardness of 2, which is less than 2.5.

Can scratch a penny, but can not scratch a steel file

Step1: Determine hardness range

A penny has a hardness of 3.5, and a steel file has a hardness of 6.5. The mineral should have a hardness greater than 3.5 and less than 6.5.

Step2: Select mineral

Apatite has a hardness of 5, which fits the range.

Can scratch all other minerals

Step1: Recall hardness property

The hardest mineral on Mohs' scale can scratch all others.

Step2: Select mineral

Diamond has a hardness of 10 (the highest on the scale).

Answer:

• Can be scratched by your fingernail: Gypsum (2)
• Can scratch a penny, but can not scratch a steel file: Apatite (5)
• Can scratch all other minerals: Diamond (10)