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 $Ln(III)$ ions decreases in general with increasing atomic number.
• B
  $Ln(III)$ compounds are generally colourless.
• C
  $Ln(III)$ hydroxides are mainly basic in character.
• D
  Because of the large size of the $Ln(III)$ ions,the bonding in its compounds is predominantly ionic in character.