Assign $A, B, C, D$ for the given type of reaction: $Fe(CN)_3 \downarrow + 3KCN \longrightarrow K_3[Fe(CN)_6]$

On adding excess of ammonium hydroxide to a copper sulphate solution:

Given the following reactions:
$Ag^{+} + NH_3 \rightleftharpoons [Ag(NH_3)]^+ ; K_1 = 1.6 \times 10^3$
$[Ag(NH_3)]^+ + NH_3 \rightleftharpoons [Ag(NH_3)_2]^+ ; K_2 = 6.8 \times 10^3$
What is the formation constant for $[Ag(NH_3)_2]^+$?

When aqueous sodium hydroxide is added to an aqueous solution of chromium $(III)$ ions,a green-blue precipitate is first formed which re-dissolves to give a green solution. This green colour is due to

Nitrate is confirmed by the ring test. The brown color of the ring is due to the formation of:

Identify the correct statements from the following:
$A$. $[Fe(C_2O_4)_3]^{3-}$ is the most stable complex among $[Fe(OH)_6]^{3-}$, $[Fe(C_2O_4)_3]^{3-}$ and $[Fe(SCN)_6]^{3-}$.
$B$. The stability of $[Cu(NH_3)_4]^{2+}$ is greater than that of $[Cu(en)_2]^{2+}$.
$C$. The hybridization of $Fe$ in $K_4[Fe(CN)_6]$ is $d^2sp^3$.
$D$. $[Fe(NO_2)_3Cl_3]^{3-}$ exhibits linkage isomerism.
$E$. $NO_2^-$ and $SCN^-$ ligands are $NOT$ ambidentate ligands.
Choose the correct answer from the options given below: