JEE Main · 2019 · 11 Jan 2019 · Shift 2 · p-Block Elements

The relative stability of +1 oxidation state of group 13 elements follows the order:

(A) $Al < Ga < TI < In$
(B) $TI < In < Ga < AI$
(C) $Ga < AI < In < TI$
(D) $Al < Ga < In < TI$ ✓ Correct

Answer: (D)

Solution

The stability of the

+ 1

state in group 13 grows down the group because of the inert pair effect: the

n s^{2}

electrons become increasingly reluctant to bond as the shielding by the intervening

d

and

f

electrons is poor. So the

+ 1

state becomes more favourable relative to

+ 3

on descending, giving the order

Al < Ga < In < Tl

JEE Main · 2019 · 11 Jan 2019 · Shift 2 · Single correct option

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