Question

Which of the following statements is not correct ?

• A. $Lu(OH{)}_3$ is less basic than $La(OH{)}_3$
• B. In lanthanide series, ionic radius of $L{a}^{3+}-L{n}^{3+}$ ion increases
• C. La is actually an element of transition series rather lanthanide
• D. Atomic radius of Zr and Hf are same because of lanthanide contraction

Answer 1

Answer: (A), (B)

The correct options are
A $Lu(OH{)}_3$ is less basic than $La(OH{)}_3$
B In lanthanide series, ionic radius of $L{a}^{3+}-L{n}^{3+}$ ion increases

$Lu(OH{)}_3$ is less basic than $La(OH{)}_3$.
Due to lanthanoid contraction, the size of the tripositive lanthanoid ion regularly decreases with increase in the atomic number from $L{a}^{3+}$ to $L{u}^{3+}$. This decreases the basic character.