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Carbon and Silicon atoms have four valence electrons each. At room temperature-

Carbon and Silicon atoms have four valence electrons each. At room temperature- Correct Answer the number of free electrons is significant only in Silicon

The correct answer is option 2) i.e. the number of free electrons is significant only in Silicon

CONCEPT:

  • Energy band gap: It is the distance between the valence band and conduction band of material.
    • Electrons in the conduction band are responsible for current.
    • The gap between the valence band and conduction band represents the minimum energy required by an electron in the valence band to jump to the conduction band.
    • The energy bandgap for a few materials are as follows

EXPLANATION:

  • As we know, Carbon is an insulator and Silicon is a semiconductor.
  • Thus, the energy bandgap for Carbon is much greater than that of Silicon.
  • At room temperature, the valence electrons of Silicon can gain energy to cross the band gap and move into the conduction band. So, there is a significant number of free electrons for conduction in Silicon at room temperature.
  • However, as the bandgap is more in Carbon, only very few electrons will jump into the conduction band. As a result, there is no significant number of electrons in the conduction band even at room temperature.
  • Thus, at room temperature, the number of free electrons is significant only in Silicon.

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