Question

Identify the WRONG statement from the following. In an intrinsic semiconductor ______.

Options

• The number of free electrons increases with temperature.

• The number of free electrons is less than that in a conductor.

• There are no free electrons at absolute zero temperature.

• There are no free electrons at any temperature except absolute zero.

Answer 1

There are no free electrons at any temperature except absolute zero.

Explanation:

In an intrinsic semiconductor:

• At absolute zero (0 K): No free electrons exist, all electrons are tightly bound in the valence band, and the conduction band is completely empty.
• Above absolute zero: Thermal energy excites electrons across the band gap into the conduction band, creating free electrons.

Option D says "no free electrons at any temperature except absolute zero", , which implies electrons are absent everywhere except at 0 K. This is the exact opposite of the truth. Free electrons are absent at 0 K and present above 0 K.