Which of the following is NOT an insulator?

Insulator:

• An insulator is a material that does not conduct electrical current.
• The vacuum is also an insulator but is not actually material.
• Most electrical conductors are covered by insulation.
• Magnet wire is coated with an extremely thin layer of insulation so that more turns or larger wire may be used in the winding of transformers.
• The insulator is a material in which the electron does not flow freely.
• The atom of the insulator has tightly bound electrons.
• Examples of insulators include plastics, paper, rubber, glass and bakelite

Conductor:

• The conductor is the opposite of the Insulator.
• A Conductor is an object that allows the free flow of charge.
• Examples of conductors include silver, copper, gold, aluminum, iron.