Question
Knowing that the chemistry of lanthanoids $$(Ln)$$ is dominated by its + 3 oxidation state, which of the following statements is incorrect ?
A.
The ionic size of $$Ln\left( {{\text{III}}} \right)$$ decrease in general with increasing atomic number.
B.
$$Ln\left( {{\text{III}}} \right)$$ compounds are generally colourless.
C.
$$Ln\left( {{\text{III}}} \right)$$ hydroxide are mainly basic in character.
D.
Because of the large size of the $$Ln\left( {{\text{III}}} \right)\,ions$$ the bonding in its compounds is predominantly ionic in character.
Answer :
$$Ln\left( {{\text{III}}} \right)$$ 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.