Most common oxidation states shown by cerium are

Which of the following properties decreases on moving from $Ce$ to $Lu$?

Consider the following statements:
$I$. $La(OH)_3$ is the least basic among hydroxides of lanthanides.
$II$. $Zr^{4+}$ and $Hf^{4+}$ possess almost the same ionic radii.
$III$. $Ce^{4+}$ can act as an oxidizing agent.
Which of the above is/are true?

$A$ reduction in atomic size with an increase in atomic number is a characteristic of elements of

Which one of the following lanthanide ions does not exhibit paramagnetism?

Which one of the following statements related to lanthanons is incorrect?