I believe that there are 12 oxygen atoms in aluminum sulfate, And 1 Sulfur and 2 aluminum. If you need anything else let me know.
Scholarly research uses credible sources
Answer is: a. harder.
Friedrich Mohs devised a scale that tested mineral hardness, which means the resistance of a mineral to being scratched. This scale (from 1 to 10) is known as the Mohs Hardness Test.
For examples:
fingernail (hardness = 2.5).
copper penny (hardness = 3)
glass plate or steel knife (hardness = 5.5)
steel file (hardness = 6.5).
According to this scale hardness of the mineral is between 5.5 and 6.5.
A and B are most closely on the diagram because if you look at A and D is on another side of the diagram than A is. B is on the same side as A. According to “Present time” A B and D are at the top of a arrow but it seems B is a little further down from the arrow if you look closely. This doesn’t change the fact that it’s closer to A.