AIIMS2012ChemistryChemical Bonding and Molecular Structure
Assertion : La ( OH )₃ is more basic than Lu ( OH )₃ . Reason : Size of Lu ³⁺ increases and shows more covalent character.
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion
- BIf both assertion and reason are true but reason is not the correct explanation of assertion
- CIf assertion is true but reason is false
- DIf both assertion and reason are false.
Correct answer
C. If assertion is true but reason is false
Step-by-step solution
Due to lanthanide contraction, the size of Lu ³⁺ is decreased and therefore Lu ( OH )₃ shows more covalent character (Small cation, more is covalent character - Fajan's rule). Thus La ( OH )₃ is more ionic and thus more basic.