Name the hardest artificial substance known?

If a reaction has g of -136kj at 110°c, will it be spontaneous at this temperature (110°c)? yes or no

Which sentence about particles in matter is true? a. atoms are present in solids and liquids but not in gases. b. the particles of matter are in constant motion. c. the same kinds of atoms are found in different elements. d. when a solid changes to a liquid, the sizes of the particles change.

Many ionic compounds and a few highly polar covalent compounds are because they completely ionize in water to create a solution filled with charged ions that can conduct an electric current.