Which of the following is an incorrect match for the precipitate (ppt) and its color?

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

Compound $X$ is tested and the results are shown in the table.

Test	Result
Aqueous $NaOH$ is added, then heated gently.	Gas given off which turns damp red litmus paper blue.
Dilute $HCl$ is added.	Effervescence, gas given off which turns lime water milky and acidified $K_2Cr_2O_7$ paper green.

Which ions are present in compound $X$?

$A$ reagent used to test the presence of $Fe^{2+}$ ion is

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

Which of the following gives a black precipitate when $H_2S$ gas is passed through its solution?