When treated with conc. $HCl$,$MnO_2$ yields a gas $(X)$ which further reacts with $Ca(OH)_2$ to generate a white solid $(Y)$. The solid $Y$ reacts with dil. $HCl$ to produce the same gas $X$. The solid $Y$ is

$Cl_{2}O_{7}$ is the anhydride of

With respect to hypochlorite,chlorate,and perchlorate ions,choose the correct statement$(s)$.
$A.$ The hypochlorite ion is the strongest conjugate base.
$B.$ The molecular shape of only the chlorate ion is influenced by the lone pair of electrons on $Cl$.
$C.$ The hypochlorite and chlorate ions disproportionate to give rise to an identical set of ions.
$D.$ The hypochlorite ion oxidizes the sulfite ion.

Which of the following compounds is thermally most stable?

Name two poisonous gases which can be prepared from chlorine gas.

Which of the following is the correct order of thermal stability of hydrogen halides $(H - X)$?