The stability of +1 oxidation state among Al, Ga, In and Tl increases in the sequence
- Al < Ga < In < Tl
- Tl < In < Ga < Al
- In < Tl < Ga < Al
- Ga < In < Al < Tl
Answer
(1) Al < Ga < In < Tl
Solution
As per NCERT, in group 13 the stability of the +1 oxidation state increases down the group because of the inert pair effect: the ns2 electrons become more reluctant to take part in bonding (poor shielding by d and f electrons).
⇒ In Tl, +1 is the more stable state; Al shows essentially only +3.
∴ Al < Ga < In < Tl
Answer: (1)