Which Of the Following is The Best Insulator?

Glass is the best insulator. Glass is an amorphous (non-crystalline) solid material. Glasses are typically brittle, and often optically transparent. The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, made of about 75% silica (SiO2) plus Na2O, CaO and several minor additives. Often, the term glass is used in a restricted sense to refer to this specific use.