It's an elemental compound
to be a hard substance.
Pure substance; it is one form of pure carbon.
A diamond is not a compound; it is formed from carbon. Even though there are trace amounts of other minerals in diamonds -- such as nitrogen, which gives diamonds a yellow case -- diamond is not a compound, because the trace minerals cannot be separated out. (According to Wikipedia: "A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions.")
If you have a silvery substance on the back surface of your diamond, it is not a diamond.
Yes, a compound is a single substance.
A compound is a pure substance.
No natural substance is equal in hardness to a diamond.
CH4 is the formula for methane meaning it is a compound substance.
Diamond is a particular elemental compound composed of carbon.
Another diamond.
compound
Diamond is a particular elemental compound composed of carbon.