$A$ compound is soluble in water. If ammonia is added,a red precipitate appears which is soluble in dilute $HCl$. The compound contains:

Which of the following options is incorrect?

An aqueous solution containing $FeSO_4$,$Al_2(SO_4)_3$,and chrome alum is treated with $Na_2O_2$ and heated,followed by filtration. The resulting products are:

The reagent used in the qualitative analysis of the $IV^{th}$ group basic radicals is:

$A$ mixture of chlorides of $Cu, Cd, Cr$ and $Fe$ was dissolved in water acidified with dil. $HCl$ and $H_2S$ gas was passed. It was filtered,and boiled later adding two drops of $HNO_3$. To this solution $NH_4Cl$ and $NH_4OH$ (or $NaOH$ in excess) were added. The filtrate shall give a test for :-

$A$ black sulphide is formed by the action of $H_2S$ on