p-Block Elements-I 1 Question 3
3. The relative stability of $+1$ oxidation state of group $13$ elements follows the order
(2019 Main, 11 Jan II)
(a) $\mathrm{Al}<\mathrm{Ga}<\mathrm{Tl}< \mathrm{In}$
(b) $\mathrm{Al}<\mathrm{Ga}< \mathrm{In} <\mathrm{Tl}$
(c) $\mathrm{Tl} < \mathrm{In} < \mathrm{Ga} < \mathrm{Al}$
(d) $\mathrm{Ga}< \mathrm{Al}< \mathrm{In} <\mathrm{Tl}$
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Answer:
Correct Answer: 3. (b)
Solution:
- The stability order of $+3$ and $+1$ oxidation states of group $13$ elements will be:
The presence of two oxidation states in $p$-block elements is due to the inert pair effect.
Because of the presence of poor shielding $d$ and $f$ -orbitals, as we move from $\mathrm{Ga}$ to $\mathrm{Tl}$, effective nuclear charge of these elements increases so as to hold the valence $n s^{2}$ electrons tightly. It causes difficulty to the ionisation of $n s^{2}$ -electrons and it remains inert, only $n p^{1}$ -electron ionises to give $+1$ oxidation state.
BETA
