Question

Out of the following impurities, which impurity is not a trivalent?

• A. Aluminium (Al)
• B. Antimony (Sb)
• C. Indium (In)
• D. Boron (B)

Hint:

Mnemonic for Trivalent: \textbf{B-Al-Ga-In} (BAGI).
Mnemonic for Pentavalent: \textbf{P-As-Sb-Bi} (PASB).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Trivalent impurities belong to Group 13 and have 3 valence electrons (Acceptors). Pentavalent impurities belong to Group 15 and have 5 valence electrons (Donors).
Step 2: Formula Application:
Group 13 (Trivalent): B, Al, Ga, In, Tl. Group 15 (Pentavalent): P, As, Sb, Bi.
Step 3: Explanation:
Aluminium, Indium, and Boron are all in Group 13 (trivalent). Antimony (Sb) is in Group 15, making it pentavalent.
Step 4: Final Answer:
Antimony (Sb) is not a trivalent impurity.