Which oxide is alkaline?

$N_2$ combines with metals to form:

Based on the compounds of group $15$ elements,the correct statement$(s)$ is (are):
$(A)$ $Bi_2O_5$ is more basic than $N_2O_5$
$(B)$ $NF_3$ is more covalent than $BiF_3$
$(C)$ $PH_3$ boils at a lower temperature than $NH_3$
$(D)$ The $N-N$ single bond is stronger than the $P-P$ single bond

The temperature required for electrolysis is maximum for which of the following hydrides?

Ionic radius (in $\mathring{A}$) of $As^{3+}$,$Sb^{3+}$ and $Bi^{3+}$ follow the order:

Which one of the elements is most metallic?