Which of the following statements is/are correct?

1) Conductor contains a large number of electrons in the conduction band at room temperature. No energy gaps exist and the valence and conduction bands overlap.

2) A semiconductor is a material in which the energy gap is so large that practically no electron can be given enough energy to jump this gap.

3) An insulator is a solid with an energy gap small enough for electrons to cross rather easily from the valence band to conduction band.