$A$ pink colored salt on dry heating becomes blue in colour. The salt may contain:

Which of the following orders are correct against the stated property?
$I$) $NaO_2 < KO_2 < RbO_2 < CsO_2$ - stability
$II$) $Mg(OH)_2 < Ca(OH)_2 < Sr(OH)_2$ - basic strength
$III$) $MgCO_3 < CaCO_3 < SrCO_3$ - thermal stability

Which of the following statements is not correct?

In which of the following are the $s$-block elements arranged in the correct order of their melting points?

Which of the following order$(s)$ is/are correct?
$(A)$ Thermal stability: $BeSO_4 < MgSO_4 < CaSO_4 < SrSO_4$
$(B)$ Melting point: $NaCl > KCl > RbCl > CsCl$
$(C)$ Solubility: $LiOH < NaOH$
$(D)$ Lattice energy: $KF > KCl > KBr > KI$

$A$ 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