Which of the comparison Zn, Cd, Hg is/are incorrect?
(I) `ZnCl_(2)` is ionic whereas ` CdCl_(2) and HgCl_(2)` is covalent
(II) Zn and Cd dissolves in dilute acid HCl liberating `H_(2)` but Hg can not
(III) Zn and cd forming with ppt. of `Zn(OH)_(2) and Cd(OH)_(2)` but Hg forms coloured ppt. of `Hg(OH)_(2)`.
(IV) All form `A_(2)^(2+)` type ion

Options

A. only III
B. I,III,IV
C. I and III
D. all of these

Answer

B