At absolute zero, Si acts as

Asked in JEE Main 2002 · Conductors, insulators and semiconductors

Answer: (3) insulator

Step-by-step solution

At 0 K no electron has thermal energy to cross the 1.1 eV gap.

The valence band is completely full and the conduction band completely empty.

With no free carriers, Si behaves as an insulator.

(1) Describes chemistry, not electrical behaviour; the question is about conduction.
(2) A metal needs a partly filled band; Si has a full valence band and empty conduction band.
(4) Si behaves as a perfect insulator at 0 K.

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