A mixture of two salt was treated as follows :
i. The mixture was heated with magnanese dioxide and concentrated sulphuric acid , when a yellowish -green gas was liberated.
ii. The mixture on heating with sodium hydroxide solution gave a gas which turned red litmus blue
iii. Its solution in water gave a blue precipitate with potassium ferricyanide and red colourtion with ammonium thiocynate
iv. The mixture was boiled with potassium hydroxide and the librated gas was bubbled through an alkline solution of `K_(2)HgI_(4)` to give a brown precipitate identify the two salts gives ionic equation for the reaction involved in the tests (i) , (ii) and (iii).

Explanation

The maxiture contain `Fe^(2+) ,NH_(4)^(oplus) + CI^(Theta)` ions (with an impurity of `Fe^(3+)` ions)

`rarr "Test of" NH_(3)` is confirmed.
`rarr "Mixture must be containing" NH_(4)Cl`
`Cl^(Theta) + MnO_(2) + H_(2)SO_(4) to underset("Greenish yellow")(Cl_(2)) uarr gas + MnSO_(4)`
Mixture + `NaOH to NH_(4)OH underset(NaOH)(to) NH_(3) uarr overset(Red)underset("Litmus")(to)` blue
`underset(KOH)(Boil) gas overset(K_(2)H_(2)I_(4))(to)` brown `NH_(3)` confirmed
`NH_(4)Cl` is confirmed.
Now `Fe^(2+) + K_(4)[(FeCN)_(6)] to underset("Ferro-ferri cyanide")(Fe[Fe(CN)_(6)]_(2)`) blue
`rarr` Mixture contains `FeCl_(2)`
Last is interseting as it signifies presence of
`Fe^(3+) (Fe^(3+) + NH_(4)CNS to Fe(SCN)_(3)]`
Either `Fe^(2+) overset("Oxidised")(to) Fe^(3+)` or may be mixture contains `FeCl_(3)`