Which of the following statements is/are true?

${\mathrm{Ag}}^{+}$ ions do not give white precipitate with concentrated HCl

.${\left[{\mathrm{AgCl}}_2\right]}^{-}\text{(soluble) }$

${\mathrm{Cu}}^{2+}$ ions produce a white precipitate when KCN solution is added in a small quantity 

$\mathrm{Cu}(\mathrm{CN}{)}_2\downarrow ⟶\underset{\left(\mathrm{White}\right)}{\mathrm{CuCN}\downarrow }+(\mathrm{CN}{)}_2\uparrow$

${\mathrm{Hg}}^{2+}$ ions give deep blue precipitate with cobalt acetate and ammonium thiocyanate

${\mathrm{Hg}}^{2+}+{\mathrm{Co}}^{2+}+4{\mathrm{SCN}}^{-}⟶\underset{(\mathrm{Deep} \mathrm{blue})}{\mathrm{Co}\left[\mathrm{Hg}(\mathrm{SCN}{)}_4\right]\downarrow }$

Black precipitate of ${\mathrm{BiI}}_3$ turns orange when heated with water.

$\mathrm{BiOI}\downarrow$ (Orange)

All options are correct.