Arrange the following in the decreasing order of their band gap energy.
(A) Carbon (diamond)
(B) Germanium
(C) Metal
(D) Silicon
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (D), (B), (C)
The band gap is the energy separating the valence band from the conduction band. It is large for an insulator, small for a semiconductor, and zero for a metal, whose bands overlap.
(A) Carbon (diamond): about 5.4 eV, an insulator.
(D) Silicon: about 1.1 eV.
(B) Germanium: about 0.7 eV.
(C) Metal: no band gap (0 eV).
Decreasing order: (A), (D), (B), (C).
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. Sn also is a group IV element but it is a metal because the energy gap in its case is 0 eV.”