Why do electrons in insulators not contribute to its conductivity?

Can an insulator be charged by the method of conduction?

Diamond is insulator, but graphite is a conductor. Why?

Why do two electrons in an orbital have opposite spin ?

For a perfect insulator coefficient of thermal conductivity is .

Why diamond behaves like an insulator?

The number of electrons in an insulator is of the same order as the number of electrons in a conductor. What is then the basic difference between a conductor and an insulator ?

The number of electrons in an insulator is of the same order as the number of electrons in a conductor. What is then the basic difference between a conductor and an insulator ?

The number of electrons in an insulator is of the same order as the number of electrons in a conductor. What is then the basic difference between a conductor and an insulator ?

perfect insulator has a _____ value of a thermal conductivity .