Question
Knowing that the chemistry of lanthanoids$$\left( {Ln} \right)$$ is dominated by its $$ + 3$$ oxidation state, which of the following statements is incorrect?
A.
The ionic size of $$Ln\,\left( {III} \right)$$ decrease in general with increasing atomic number
B.
$$Ln\,\left( {III} \right)$$ compounds are generally colourless.
C.
$$Ln\,\left( {III} \right)$$ hydroxide are mainly basic in character.
D.
Because of the large size of the $$Ln\,\left( {III} \right)$$ ions the bonding in its compounds is predominantly ionic in character.
Answer :
$$Ln\,\left( {III} \right)$$ compounds are generally colourless.
Solution :
Most of the $$L{n^{3 + }}$$ compounds except $$L{a^{3 + }}$$ and $$L{u^{3 + }}$$ are coloured due to the presence of $$f$$ -electrons.