Which of the following statement$(s)$ is(are) correct with reference to the ferrous and ferric ions?

Which of the following statement$(s)$ is/are correct with reference to $Fe^{2+}$ and $Fe^{3+}$ ions?
$(1)$ $Fe^{3+}$ gives brown colour with potassium ferricyanide
$(2)$ $Fe^{2+}$ gives blue colour with potassium ferricyanide
$(3)$ $Fe^{3+}$ gives red colour with potassium thiocyanate
$(4)$ $Fe^{2+}$ gives brown colour with ammonium thiocyanate

$A$ salt reacts with dilute $HCl$ to produce a gas with a pungent smell and yellow crystals. When tested,the salt gives a green flame. With potassium chromate,the salt gives yellow crystals. Therefore,the salt is.......

Which of the following match is $INCORRECT$ :

Aqueous solution of which of the following cation gives a precipitate with potash alum?

Which one among the following pairs of ions cannot be separated by $H_2S$ in dilute hydrochloric acid?