$PbO_2$ reacts with concentrated $HNO_3$. The gas evolved is:

$A$ cyclic skeleton of silicon and oxygen can be constructed by the silicate ion composition:

$A$ black sulphide precipitate when treated with ozone becomes white. The white compound is:

Match the following:

List-$I$ (Compound)	List-$II$ (Use)
$A$. Kieselghur	$I$. Chromatographic material
$B$. Silica gel	$II$. Softening of hard water
$C$. $ZSM-5$	$III$. Filtration plants
$D$. Hydrated zeolites	$IV$. To convert alcohol directly into gasoline

Assertion : $Pb^{4+}$ compounds are stronger oxidizing agents than $Sn^{4+}$ compounds.
Reason : The higher oxidation states for the group $14$ elements are more stable for the heavier members of the group due to 'inert pair effect'.

Among the following oxides,which one is weakly basic and yet a powerful oxidant?