1. Impure diamond is used to cut glass because it is the hardest substance and can easily exert force required for cutting.
2. Pure gold is a very soft metal. It cannot be molded into ornaments so it is mixed with copper and nickel so that it becomes harder and bit cheaper also.
3. It is a shiny grey metal, in a solid state at room temperature. It can withstand high temperature because it has the highest melting point among metals. Hence, it is used in electric bulbs.
