Q. The stability of +1 oxidation state increases in the sequence:
A) Tl < In < Ga < Al
B) In < Tl < Ga < Al
C) Ga < In < Al < Tl
D) Al < Ga < In < Tl
Explanation
[Solution from source] Because of the inert pair effect, the ns² pair becomes less available down group 13, so the +1 state becomes more stable from Al to Tl: Al < Ga < In < Tl. Tl⁺ is the most stable +1 ion of the group. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.