The reaction of nitroprusside anion with sulphide ion gives purple colouration due to the formation of

Which of the following complexes is octahedral,diamagnetic,and the most stable?

$CuSO_4$ reacts with $KCN$ solution and forms

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$NiCl_2 + NH_3$ (Excess) $\longrightarrow [Ni(NH_3)_6]^{2+}$

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:

When $100 \ mL$ of $0.2 \ M$ solution of $CoCl_3 \cdot x NH_3$ is treated with excess of $AgNO_3$ solution,$3.6 \times 10^{22}$ ions are precipitated. The value of $x$ is $\left(N_A = 6 \times 10^{23} \ mol^{-1}\right)$