Question

The relative stability of $ + 1$oxidation state of group 13 elements following the order:
(A) $Al < Ga < Tl < In$
(B) $Ti < \operatorname{I} n < Ga < Al$
(C) $Al < Ga < In < Tl$
(D) $Ga < Al < In < Tl$

Answer 1

Hint: Group 13 or the beron family is the first group of periodic tables in $p - $block Members of Boron family are Boron , Aluminum, Gallium, Indium and Thallium. The general electronic configuration of this group is $n{s^2}n{p^1}.$

Complete step by step answer:
Oxidation state is a number of elements that represents the number of electrons gained or lost by the atom in a compound generally, the oxidation state exhibited by all the elements of a group is the same.
For example, the general oxidation state of the Boron family is $ + 3$, though $ + 1$ state is also exhibited by some elements down the group.
The reason for the $ + 1$ oxidation state of this group is inert pair effect.
Inert pair effect :- Two electrons in the valence S-orbital is reluctant to take shielding of –d and –f orbital in heavy elements. Due to this effect, the lower oxidation state of an element becomes more stable as compared to the higher oxidation state.
This effect is shown by the indium and thallium of group 13. Therefore, as we move down the group, the lower oxidation state becomes more stable.
So, the arrangement of elements will be :-
$Al < Ga < In < Tl$

So, the correct answer is Option C .

Additional Information:
Boron is a non-metal. It is used to make ceramic pan handles for insulation, pots, plates etc. Aluminium is used in electrical devices, construction materials etc. Aluminium does not react with food and thus it is used to make Aluminium foils and cans. Gallium is used in semiconductors, solar cells etc. Indium is used in heat reflectors, bearings, nuclear control rods etc. thallium is used in photoelectric cells, myocardial imaging etc. it also acts as a catalyst in many reactions.

Note:
There are certain rules for calculating the oxidation state of elements
(i) The oxidation state of the free element is zero
(ii) Oxidation of group 1 elements is $ + 1$
(iii) Oxidation of group 2 elements is $ + 2$
(iv) Oxidation of group 17 elements is $ - 1$
(v) Oxidation state of oxygen is $ - 2,$ but in peroxides, it is $ - 1$
(vi) Oxidation state of $H$ is $ + 1$, but it is $ - 1$ when $H$ is combined to less electronegative element