Question:
Consider the statements in a semiconductor:
(A) There are no free electrons at \(0\;K\).
(B) There are no free electrons at any temperature.
(C) The number of free electrons increases with temperature.
(D) The number of free electrons is less than that in a conductor.
Consider the statements in a semiconductor:
(A) There are no free electrons at \(0\;K\).
(B) There are no free electrons at any temperature.
(C) The number of free electrons increases with temperature.
(D) The number of free electrons is less than that in a conductor.
(A) There are no free electrons at \(0\;K\).
(B) There are no free electrons at any temperature.
(C) The number of free electrons increases with temperature.
(D) The number of free electrons is less than that in a conductor.
Show Hint
In semiconductors, conductivity increases with temperature because the number of free electrons and holes increases due to thermal excitation.
Updated On: Jun 22, 2026
- B, C, D are true but A is false
- A, B, C are true but D is false
- A, C, D are true but B is false
- A, B, C and D are all true
Show Solution
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The Correct Option is C
Solution and Explanation
Step 1: Analyze Statement (A).
At absolute zero temperature \((0\;K)\), all electrons in a semiconductor remain bound in covalent bonds.
Hence, there are no free charge carriers.
Therefore, Statement (A) is true.
Step 2: Analyze Statement (B).
At temperatures above \(0\;K\), thermal energy breaks some covalent bonds and generates free electrons and holes.
Thus, semiconductors do have free electrons at ordinary temperatures.
Therefore, Statement (B) is false.
Step 3: Analyze Statement (C).
As temperature increases, more covalent bonds break and more electron-hole pairs are generated.
Hence, the number of free electrons increases with temperature.
Therefore, Statement (C) is true.
Step 4: Analyze Statement (D).
Conductors contain a very large number of free electrons, whereas semiconductors contain comparatively fewer free electrons.
Therefore, Statement (D) is true.
Step 5: Final conclusion.
Thus, statements A, C and D are true, but B is false.
Hence, the correct option is \[ \boxed{\text{A, C, D are true but B is false}} \]
At absolute zero temperature \((0\;K)\), all electrons in a semiconductor remain bound in covalent bonds.
Hence, there are no free charge carriers.
Therefore, Statement (A) is true.
Step 2: Analyze Statement (B).
At temperatures above \(0\;K\), thermal energy breaks some covalent bonds and generates free electrons and holes.
Thus, semiconductors do have free electrons at ordinary temperatures.
Therefore, Statement (B) is false.
Step 3: Analyze Statement (C).
As temperature increases, more covalent bonds break and more electron-hole pairs are generated.
Hence, the number of free electrons increases with temperature.
Therefore, Statement (C) is true.
Step 4: Analyze Statement (D).
Conductors contain a very large number of free electrons, whereas semiconductors contain comparatively fewer free electrons.
Therefore, Statement (D) is true.
Step 5: Final conclusion.
Thus, statements A, C and D are true, but B is false.
Hence, the correct option is \[ \boxed{\text{A, C, D are true but B is false}} \]
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