(1) The lanthanide series fill up the 5f sublevel and the actinide series fill up the 4f sublevel.
(2) There are four lanthanide metals that have properties similar to the d block. These are cerium, Ce, lutetium, Lu, and gadolinium, Gd and praseodymium, Pr
(3) The first, middle, and last member of the lanthanide series have properties of the f block and the d block.
(4) General electronic configuration of f – block elements is $(n–2)f^{1–14}(n–1)d^{0–1}ns^2$
$\begin {array} {1 1} Only (1) \\ (2) \;and \;(3) \\ (1)\;and \;(2) \\ (1),(2)\;and\;(4) \end {array}$
