p-Block Elements-I - Result 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. (a)
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
$$ B^{3+}>Al^{3+}>Ga^{3+}>In^{3+}>Tl^{3+} $$
$B^{3+}$ does not exist in free states. All B(III) compounds are covalent.
- +1 oxidation states
$B^{+}<Al^{+}<Ga^{+}<In^{+}<Tl^{+}$
$B^{+}$does not exist in ionic as well covalent compounds.
