In a silicon intrinsic semiconductor, the forbidden energy gap between the valence band and the conduction band is approximately equal to
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \( 1.1\,\mathrm{eV} \)
The forbidden energy gap \( E_g \) separates the top of the valence band from the bottom of the conduction band. For a semiconductor it is small (about 1 eV), so a few electrons can cross it at room temperature.
For silicon, \( E_g \approx 1.1\,\mathrm{eV} \) (for germanium it is about \( 0.7\,\mathrm{eV} \)).
NCERT (2026-27):
Extrinsic Semiconductor – “… The difference in the resistivity of C, Si and Ge depends upon the energy gap between their conduction and valence bands. For C (diamond), Si and Ge, the energy gaps are 5.4 eV, 1.1 eV and 0.7 eV, respectively.”