whats an element tat can be used as an insulator? why?

Answer 1

There are many elements which can be used as insulators in gas phase, such as N2, He, Ne, Ar, Kr, or even O2. The well known gas phase insulator is simply the air, as used in many capacitors in the past and present.

There are two elements which can be used as insulator: diamond carbon is one and several forms of Selenium is the other.

Isolated selenium occurs in several different forms, the most stable of which is a dense purplish-gray semimetal (semiconductor) form that is structurally a trigonal polymer chain. It conducts electricity better in the light than in the dark, and is used in photocells (see allotropic section below). Selenium also exists in many NON-CONDUCTIVE forms: a black glass-like allotrope, as well as several red crystalline forms built of eight-membered ring molecules, like its lighter chemical cousin sulfur.