Sapphires and rubies are forms of the mineral corundum, A1,0g. Corundum is one of the hardest known natural materials.
The hardness of fonic compounds depends on the structure of the crystal
and the strength of the ionic bonds. The distance between the aluminum
lons (AP) and oxide ions (027 is 191 pm. Use Coulomb's law to explain how
the bonding in Al2O, influences its properties.

I'm not sure but i will try to find out

Yes it would be a physical change.

1. why does the same side of the moon always face earthc.the rotational period of the moon is equal to one revolution around earth2. which is greater the moons period of rotation or its period of revolution  b.the moons revolution period around earth3.what was the major accomplishment of the apollo missions  d.landing on and exploring the moon4. which of these space missions involved the deployment of lunar rovers d.apollo5. which scientists are going to explore next on kepler-186fd. evidence of existence of life6.which mission is not going to explore the outside of the solar systemb.safir7.which technology limit the future of space exploration b. scientist must first develop certain technologies before missions can be completed.