Which of the following does not exist?

The number of non-ionisable protons present in the product $B$ obtained from the following reaction is:
$3C_{2}H_{5}OH + PCl_{3} \rightarrow 3C_{2}H_{5}Cl + H_{3}PO_{3} (A)$
$H_{3}PO_{3} + PCl_{3} \rightarrow H_{4}P_{2}O_{5} (B) + HCl$

With respect to graphite and diamond,which of the statement$(s)$ given below is (are) correct?
$(A)$ Graphite is harder than diamond.
$(B)$ Graphite has higher electrical conductivity than diamond.
$(C)$ Graphite has higher thermal conductivity than diamond.
$(D)$ Graphite has higher $C-C$ bond order than diamond.

Suggest a reason as to why $CO$ is poisonous.

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 $GeX_4$.

Mark the gas which turns lime water milky.