Question

Two statements are given one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below.
Assertion (A): A hole is an apparent free particle with effective positive electronic charge.
Reason (R): A hole is not necessarily a vacancy left behind by an electron in the valence band.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Both Assertion (A) and Reason (R) are false.

Hint:

In semiconductors, holes are always defined as the absence of electrons in the valence band. They act like positive charges and contribute to current flow.

Answer 1

The Correct Option is C

Assertion (A) is true: In a semiconductor, a hole is the absence of an electron in the valence band. It behaves like a positively charged free particle with an effective mass and moves under an electric field in the opposite direction of electrons. Reason (R) is false: A hole is always a vacancy created in the valence band when an electron gets excited to the conduction band. It is not just a general concept of vacancy; it is specifically defined within the context of band theory in solids. Therefore, while the assertion is correct, the reason given does not match physical principles and is incorrect.