In ${K_4}[Fe(CN)_6]$,$Fe$ is in the form of

Choose the correct statements from the following:
$A$. Ethane$-1, 2-$diamine is a chelating ligand.
$B$. Metallic aluminium is produced by electrolysis of aluminium oxide in the presence of cryolite.
$C$. Cyanide ion is used as a ligand for the leaching of silver.
$D$. Phosphine acts as a ligand in Wilkinson's catalyst.
$E$. The stability constants of $Ca^{2+}$ and $Mg^{2+}$ are similar with $EDTA$ complexes.
Choose the correct answer from the options given below:

The formula of the product formed, when sodium thiosulphate solution is added to silver bromide is

The solubility of silver bromide in hypo solution is due to the formation of :

Which one will give $Fe^{3+}$ ions in solution?

$A$ brown ring is formed in the ring test for $NO_{3}^{-}$ ion. It is due to the formation of :-