Question
The stability of +1 oxidation state increases in the sequence
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Al < Ga <In < Tl
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Tl < In <Ga< Al
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In < Tl < Ga < Al
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Ga < In < Al < Tl
Solution
A.
Al < Ga <In < Tl
Stability of lower oxidation states increases on moving down a group due to inert pair effect.
The given elements belongs to third group. These elements mainly exhibit +3 and +1 oxidation state. As we know the stability of lower oxidation state ie, +1 state, increases on moving down a group, the sequence of stability is
Al< Ga< In <Tl
