Limiting compositions of $f$-block hydrides are

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.

More number of oxidation states are exhibited by the actinoids than by the lanthanoids. The main reason for this is

The number of $f$ electrons in the ground state electronic configuration of $Np$ $(Z=93)$ is ....... .

Consider the following two statements:
$Statement-I:$ Among $Mg, Al, Mg^{2+}, Al^{3+}$,the one having the smallest size is $Al^{3+}$.
$Statement-II:$ $Eu$ has an exceptionally high atomic radius among lanthanide elements.
The correct answer is:

What are the products formed when lanthanoids $(Ln)$ react with $1$. $H_2O$ and $2$. $N_2$?