$CO$ is a stronger ligand than $Cl^{-}$ because:

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:

Which of the following complex ions has the least stability?

Which of the following complexes represents maximum stability?

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

What is a spin-free complex?