Mercury is a liquid at $0 \, ^\circ C$ because of

Select the correct option.

Which of the comparison regarding $Zn, Cd, Hg$ is/are incorrect?
$(I)$ $ZnCl_2$ is ionic whereas $CdCl_2$ and $HgCl_2$ are covalent
$(II)$ $Zn$ and $Cd$ dissolve in dilute acid $(HCl)$ liberating $H_2$ but $Hg$ cannot
$(III)$ $Zn$ and $Cd$ form white ppt. of $Zn(OH)_2$ and $Cd(OH)_2$ but $Hg$ forms coloured ppt. of $HgO$ or $Hg(OH)_2$
$(IV)$ All form $M_2^{2+}$ type ion

The transition metal used as a catalyst is

Which of the following orders is correct for the property given?

Identify the correct option:
$(I)\ AgCl$ is not soluble in $H_2O$ but soluble in $KCN$.
$(II)\ Zn$ when reacts with cold v.v. dil $HNO_3$ gives $NH_4NO_3$.
$(III)\ CuSO_4$ reacts with $KI$ to form $Cu_2I_2 + K_2SO_4$.
$(IV)\ CuSO_4 \cdot 5H_2O \xrightarrow{1000\,^oC}$ The gases liberated are $SO_2$ and $O_2$.