Zn2+
Ni2+
Co2+
Mn2+
Zn2+ ions react with H2S to form a white precipitate of ZnS
Zn2+ + H2S → ZnS↓ + 2H+
ZnS and MnS are soluble in cold dil HCl while NiS and CoS are insoluble.
ZnS produces a white precipitate of zinc hydroxide with NaOH
ZnS + 2NaOH → Zn(OH)2↓ + Na2S
ZnS forms a bluish-white ppt with basic potassium ferrocyanide
2ZnS + K4[Fe(CN)6] → Zn2[Fe(CN)6]↓ (bluish white) + 2K2S