Solid State

Which of the following material is not a semiconductor.

1. Copper oxide
2. Graphite
3. Silicon
4. Germanium

Answer

(2) Graphite

Solution

Si, Ge — small band gap ⇒ semiconductors; copper oxide (Cu2O) ⇒ also a semiconductor

∵ in graphite each C is sp2 and the fourth electron is delocalised over the layers

⇒ graphite is a good conductor, not a semiconductor

Answer: (2)