Which of the following is an insulator?

Options

A. White tin
B. Gray tin
C. Diamond
D. Germanium

Answer

3

Explanation

The following figures provides an ans wer to the question why don't slid substance like wood glass and diamond conduct electricity as metals do

Basically, the electrical conductivity of a solid depends on the spacing and the state of occupancy of the energy bands (valance band and conduction band).In metals ,valance bands are adjacent to their conduction bands.(i.e, the energy gap is virtually nonexistent) and therefore metals readily act as conductors.
In an unsulator the gap between the filled valence band and the next higher unoccupied band (conduction band) is considerably greater than that in a metal.Consequently much more energy is required to excite an electrons into the conduction band.Lacking this energy ,electrons can't jumb to conduction band and can't move freely,Glass,wood and rubber are typical insulators.
Diamond is an insulator,germanium and grey are semiconductors whilst white is a metal.
Note that `Si.Ge` and gray tin have the same crystal structure as diamond.