Question

Thallium belongs to group : 13.The stable oxidation state of thallium is plus 1 instead of plus 3 this is because of 1)Lanthanide contraction 2)Anomalous expansion 3)Inert pair effect 4)Bridge contraction​

Answer 1

Ans : 3. inert pair effect

Due to inert pair effect Thallium +1 oxidation state is more stable than +3 oxidation state. Due to presence of d and f orbital in inner shells which have poor shielding effect, it has high effective nuclear charge.

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