Question
Which of the following statement is not correct ?
A.
$$La{\left( {OH} \right)_3}$$ is less basic than $$Lu{\left( {OH} \right)_3}.$$
B.
In lanthanide series ionic radius of $$L{n^{3 + }}\,ions$$ decreases.
C.
$$La$$ is actually an element of transition series rather than lanthanide series.
D.
Atomic radii of $$Zr$$ and $$Hf$$ are same because of lanthanide contraction.
Answer :
$$La{\left( {OH} \right)_3}$$ is less basic than $$Lu{\left( {OH} \right)_3}.$$
Solution :
$$La{\left( {OH} \right)_3}$$ is more basic than $$Lu{\left( {OH} \right)_3}.$$ This is because ionic size of $$L{a^{3 + }}\,ion$$ is more than$$L{u^{3 + }}\,ion$$ (Fajan's rule).