$AgCl$ precipitate dissolves in ammonia due to the formation 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:

Transition elements in lower oxidation states act as Lewis acid because

$AgNO_3 \xrightarrow{\Delta} (W) + (X) + O_2$
$(X) + H_2O \longrightarrow HNO_2 + HNO_3$
$(W) + HNO_3 \longrightarrow Y + NO + H_2O$
$(Y) + Na_2S_2O_3(\text{excess}) \longrightarrow (Z) + NaNO_3$
Identify $(W)$ to $(Z)$.

Which one of the following has the highest molar conductivity?

Which of the following species exhibits both $LMCT$ and paramagnetism?