The percentage of lanthanides and iron,respectively,in misch metal are

What is the correct electronic configuration of $Th$ $(Z=90)$?

Find the atomic number of the element at which pairing in the $4f$ orbital starts.

The incorrect statement among the following is:

The chemistry of the actinoid elements is not so smooth as that of the lanthanoids. Justify this statement by giving some examples from the oxidation states of these elements.

Write a note on oxidation states shown by lanthanoids.