Tin (Sn) is a group IV element, like silicon and germanium. Yet tin is a metal. This is because
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → its energy gap is 0 eV
A group IV element can behave as an insulator, a semiconductor or a metal. Which one it is depends on the energy gap between its valence band and conduction band.
Option (1) its energy gap is 0 eV — Correct. With no gap there is no forbidden band to cross. Electrons move freely into the conduction band, as in a metal.
Option (2) its energy gap is about 0.2 eV, smaller than that of germanium — Incorrect. A gap of 0.2 eV is small, but it is not zero. Solids with a gap from about 0.2 eV to 3 eV are semiconductors.
Option (3) its energy gap is larger than that of diamond — Incorrect. Diamond has a gap of 5.4 eV and is an insulator. An even larger gap would make tin an insulator too.
Option (4) its energy gap is about 1.1 eV, the same as that of silicon — Incorrect. A gap of about 1.1 eV is what makes silicon a semiconductor. With this gap tin would also be a semiconductor.
NCERT (2026-27):
Extrinsic Semiconductor – “… 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.”