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+

(1) A3+andHg2+→H2SH+⟶HgS↓(black) + Al3+(in solution) (2) Cu2+ and Zn2+→H2SH+CuS↓ (black)+Zn2+ (in solution)  (3) Cd2+ and Zn2+→H2sH+ ⟶CdS↓( yellow )+Zn2+ (in solution)