Question

The most basic hydroxide from following is?

• A. $Pr\left(OH{)}_3\right(Z=59)$
• B. $Sm\left(OH{)}_3\right(Z=62)$
• C. $Ho\left(OH{)}_3\right(Z=67)$
• D. $La\left(OH{)}_3\right(Z=57)$

Answer 1

The correct option is D $La\left(OH{)}_3\right(Z=57)$

$La(OH{)}_3$ is most basic due to lanthanoid contraction. Due to lanthanoid contraction, the basicity of hydroxides decreases from $La(OH{)}_3$ to $Lu(OH{)}_3$.

Hence, the correct option is $D$.