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Question: Answered & Verified by Expert
Aluminium is usually found in +3 oxidation state. In contrast, thallium exists in +1 and +3 oxidation states. This is due to:
ChemistryClassification of Elements and Periodicity in PropertiesJEE MainJEE Main 2019 (09 Jan Shift 1)
Options:
  • A Diagonal relationship
  • B Lattice effect
  • C Lanthanoid contraction
  • D Inert pair effect
Solution:
2255 Upvotes Verified Answer
The correct answer is: Inert pair effect
Reluctance in tendency of s-electrons to participate in bonding on moving top to bottom in p-block elements is called inert pair effect. Due to inert pair effect +1 is very unstable in aluminium.

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