$$\ce{Zn^2+ <=>[+ 2OH-][+ 2H+] $\underset{\text{amphoteric hydroxide}}{\ce{Zn(OH)2 v}}$ <=>[+ 2OH-][+ 2H+] $\underset{\text{tetrahydroxozincate}}{\ce{[Zn(OH)4]^2-}}$}$$
$$ = Center
$$\ce{Zn^2+ <=>[+ 2OH-][+ 2H+] $\underset{\text{amphoteric hydroxide}}{\ce{Zn(OH)2 v}}$ <=>[+ 2OH-][+ 2H+] $\underset{\text{tetrahydroxozincate}}{\ce{[Zn(OH)4]^2-}}$}$$$\ce{Hg^2+ ->[I-] $\underset{\mathrm{red}}{\ce{HgI2}}$ ->[I-] $\underset{\mathrm{red}}{\ce{[Hg^{II}I4]^2-}}$}$
$ = left
$\ce{Hg^2+ ->[I-] $\underset{\mathrm{red}}{\ce{HgI2}}$ ->[I-] $\underset{\mathrm{red}}{\ce{[Hg^{II}I4]^2-}}$}$
chemical forumla တွေကတော့ ပုံပါအတိုင်းပါပဲ xD