Formation of which complex, among the following, is not a confirmatory test of ${\mathrm{Pb}}^{2+}$ ions

State one relevant observation for of the following:

Lead nitrate solution is treated with sodium hydroxide solution dropwise till it is in excess.

A mixture of two salts is used to prepare a solution $\mathrm{S},$ which gives the following results:

$\mathrm{White} \mathrm{precipitate}\left(\mathrm{s}\right) \mathrm{only}\underset{\mathrm{Room} \mathrm{temperature}}{\overset{\mathrm{Dilute} \mathrm{NaOH}\left(\mathrm{aq}\right)}{\leftarrow }}\underset{\left(\mathrm{aq}. \mathrm{solution} \mathrm{of} \mathrm{the} \mathrm{salts}\right)}{\mathrm{S}}\underset{\mathrm{Room} \mathrm{temperature}}{\overset{\mathrm{Dilute} \mathrm{HCl}\left(\mathrm{aq}\right)}{\to }}\mathrm{White} \mathrm{precipitate}\left(\mathrm{s}\right) \mathrm{only}$

The correct option $\left(\mathrm{s}\right)$ for the salt mixture is(are)

What are the cations present in the salt ?

A solution of a salt gives a precipitate on treatment with dilute HCl. The precipitate formed is filtered off and treated with NH₃ whereby it turns black. The cation present in the salt is

Balance the chemical equation

$\mathrm{Pb}{\left({\mathrm{CH}}_3\mathrm{COO}\right)}_2 + {\mathrm{H}}_2\mathrm{S} \to \mathrm{PbS}\downarrow + \mathrm{\_\_\_\_\_} {\mathrm{CH}}_3\mathrm{COOH}$