Which of the following electronic configurations belongs to $s-$block elements?

$A$ red coloured mixed oxide $(X)$ on treatment with conc. $HNO_3$ gives a compound $(Y).$ $(Y)$ with $HCl$ produces a chloride compound $(Z)$ which can also be produced by treating $(X)$ with conc. $HCl.$ Compounds $(X),$ $(Y),$ and $(Z)$ will be

What is the nature of metal nitrates?

Match column-$I$ with column-$II$ :

column-$I$	column-$II$
$a$. $Ra$	$p$. Aeroplane industry
$b$. $K$	$q$. Down cell
$c$. $Li$	$r$. Photo electric cell
$d$. $Na$	$s$. Radioactive

Consider three metal chlorides $x$,$y$ and $z$,where $x$ is water soluble at room temperature,$y$ is sparingly soluble in water at room temperature and $z$ is soluble in hot water. $x$,$y$ and $z$ are respectively:

The correct statements among the following are:
$(A)$ $BeH_2$ and $MgH_2$ are polymeric in nature.
$(B)$ $LiH$ is unreactive to oxygen at moderate temperatures.
$(C)$ $BeH_2$ and $MgH_2$ possess significant covalent character.
$(D)$ The stability of alkali metal hydrides follows the order $LiH < NaH < KH < RbH < CsH$.