Identify the incorrect order against the stated property.

The correct statements with respect to halides of group $14$ elements are:
$I$. Both $CCl_4$ and $SiCl_4$ undergo hydrolysis
$II$. $GeX_4$ is more stable than $GeX_2$
$III$. $PbX_4$ is less stable than $PbX_2$
$IV$. Stability of dihalides decreases down the group.

Assertion : $SiF_6^{2-}$ is known but $SiCl_6^{2-}$ is not.
Reason : Size of fluorine is small and its lone pair of electrons interacts with $d-$orbitals of $Si$ strongly.

$SiCl_4$ on hydrolysis gives:

Identify $B$ in the following reaction:
$H_4SiO_4$ $\xrightarrow[{-H_2O}]{1000^{\circ}C} A$ $\xrightarrow[\Delta]{Carbon} B + CO$

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$: $H_2\underline{S}O_5 + H_2O \longrightarrow H_2SO_4 + H_2O_2$