How many of the following pairs of ions can be separated by H₂S in dilute HCl ?
Bi³⁺ and Sn⁴⁺, Al³⁺ and Hg²⁺, Cd²⁺ and Zn²⁺, Zn²⁺ and Cu²⁺, As³⁺ and Sb³⁺

${\left.\left(1\right) \mathrm{A}\right|}^{3+}\mathrm{and}{\mathrm{Hg}}^{2+}\underset{{\mathrm{H}}_2\mathrm{S}}{\overset{{\mathrm{H}}^{+}}{\to }}⟶\mathrm{HgS}\downarrow \left(\mathrm{black}\right) + {\mathrm{Al}}^{3+}(\mathrm{in} \mathrm{solution})$

${\text{ (2) Cu}}^{\text{2+}}{\text{ and Zn}}^{2+}\underset{{\mathrm{H}}_2\mathrm{S}}{\overset{{\mathrm{H}}^{+}}{\to }}\text{CuS↓ (black)}+{\mathrm{Zn}}^{2+}\text{ (in solution) }$

$\text{ (3) }{\mathrm{Cd}}^{2+}\text{ and }{\mathrm{Zn}}^{2+}\underset{ }{\underset{{\mathrm{H}}_2\mathrm{s}}{\overset{{\mathrm{H}}^{+}}{\to }}}⟶\mathrm{CdS}\downarrow \left(\text{ yellow }\right)+{\mathrm{Zn}}^{2+}\text{ (in solution) }$