The outer electronic structure of lawrencium (atomic number $103$) is

Assertion : Ionisation enthalpies of the early actinoids are lower than for early lanthanoids.
Reason : $5f$ electrons are more effectively shielded from nuclear charge than $4f$ electrons.

Which of the following elements shows the maximum number of different oxidation states in its compounds?

Which of the following elements are analogous to the lanthanides?

Fill in the blanks:
$1.$ The size of $M^{3+}$ ions in the actinoid series ........... with an increase in atomic number.
$2.$ The common oxidation state of elements in the actinoid series is .......... .
$3.$ The appearance of elements in the actinoid series is like .......... .

Determine the correct $(T)$ and incorrect $(F)$ statements from the following:
$(a)$ $Lu^{3+}$ and $Yb^{2+}$ are not paramagnetic.
$(b)$ Sheets are made from mischmetal.
$(c)$ Pipes are made from mischmetal.