Which of the following statements is true about energy

Solution

In solids, the electrical conductivity depends on the arrangement and occupancy of energy bands. In conductors (metals) , the valence band and conduction band overlap , allowing electrons to move freely even without external energy. This overlap explains their high conductivity, as electrons are readily available for conduction. ●      (A) Incorrect : Metals do not have a large forbidden energy gap; in fact, they have no gap or the bands overlap , allowing free electron movement.

●      (C) Incorrect : Insulators have a large forbidden energy gap (typically >5 eV), not zero. Zero gap would imply high conductivity.

●      (D) Incorrect : At 0 K , semiconductors have a completely filled valence band and an empty conduction band . The conduction band becomes partially filled only at higher temperatures due to thermal excitation.

Thus, option (B) correctly describes the band structure of conductors.