Question

Most basic hydroxide among the following is:

• A. $Lu(OH{)}_3$
• B. $Eu(OH{)}_3$
• C. $Yb(OH{)}_3$
• D. $Ce(OH{)}_3$

Answer 1

The correct option is D $Ce(OH{)}_3$

Due to lanthanide contraction, the size of $M^{3+}$ ions $[i.e,L{u}^{3+},E{u}^{3+},Y{b}^{3+}$ and $C{e}^{3+}]$ decreases and thus, the basic strength of their hydroxides decreases. The order of size of given $M^{3+}$ ions is $C{e}^{3+}>E{u}^{3+}>Y{b}^{3+}>L{u}^{3+}$
$\therefore$ The order of basic strength of hydroxides is $Ce(OH{)}_3>Eu(OH{)}_3>Yb(OH{)}_3>Lu(OH{)}_3$(most basic).