For bleaching powder,which of the following statements is incorrect?

Among the following,the correct statements are:
$I$. Germanium exists only in traces.
$II$. $PbF_4$ molecule is tetrahedral in shape.
$III$. $GeX_2$ is more stable than $GeX_4$.

Which of the following is not correct?

Mark the gas which turns lime water milky.

Consider the following statements:
$I$. In diamond,each carbon atom is $sp^3$-hybridised.
$II$. Graphite has planar hexagonal layers of carbon atoms.
$III$. Silicones being surrounded by non-polar alkyl groups are water repelling in nature.
$IV$. The order of catenation in group $14$ elements is $Si > C > Sn > Ge > Pb$.
The correct statements are:

Which of the following compounds is $NOT$ acidic in nature?