p-Block Elements-I 1 Question 6
6. Aluminium is usually found in +3 oxidation state. In contrast, thallium exists in +1 and +3 oxidation states. This is due to
(2019 Main, 9 Jan I)
(a) lattice effect
(b) lanthanoid contraction
(c) inert pair effect
(d) diagonal relationship
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Answer:
Correct Answer: 6. (c)
Solution:
- Due to inert pair effect, group-13 elements $\left(n s^{2} n p^{1}\right)$ show +3 and +1 oxidation states in their compounds. Stability order of these oxidation states will be as,
- +3 oxidation states
$ \mathrm{B}^{3+}>\mathrm{Al}^{3+}>\mathrm{Ga}^{3+}>\mathrm{In}^{3+}>\mathrm{Tl}^{3+} $
$\mathrm{B}^{3+}$ does not exist in free states. All B(III) compounds are covalent.
- +1 oxidation states
$\mathrm{B}^{+}<\mathrm{Al}^{+}<\mathrm{Ga}^{+}<\mathrm{In}^{+}<\mathrm{Tl}^{+}$
$\mathrm{B}^{+}$does not exist in ionic as well covalent compounds.
