Question. On the basis of band theory of solids the semiconductors have _____________________?
  1. A party filled valence band and totally empty conduction band
  2. A completely filled valence band a totally empty conduction band and a very wide forbidden band
  3. A completely filled valence band a partially filled conduction band and a narrow forbidden band
  4. A partly filled valence band a totally empty conduction band and a wide forbidden band