Which of the following salts gives a white precipitate with $AgNO_3$ and dilute $H_2SO_4$,and also gives a green flame test?

Concentrated aqueous $NaOH$ can separate a mixture of

Consider the following reactions:
$X(aq.) \xrightarrow{K_4[Fe(CN)_6]}$ Chocolate brown ppt.
$X(aq.) \xrightarrow{AgNO_3}$ White ppt. (insoluble in dil. $HNO_3$)
Then $X$ will be:

Which compound gives a black color with $NH_4OH$?

Passing $H_2S$ gas into a mixture of $Mn^{2+}, Ni^{2+}, Cu^{2+}$ and $Hg^{2+}$ ions in an acidified aqueous solution precipitates

The ion that cannot be precipitated by both $HCl$ and $H_2S$ is