A salt on treatment with dil. HCl gives a pungent smelling gas and a yellow precipitate. The salt gives green flame test and a yellow precipitate with potassium chromate. The salt is

Since the salt on treatment with dil. HCl gives a pungent smelling gas $\left(S{O}_2\right)$  and a yellow ppt., it must contain $S_2{O}_3^{2-}$ (thiosulphate ion) and further since it gives green flame test, it must contain $B{a}^{2+}$  ion. Hence salt is $Ba{S}_2{O}_3.$