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 presence of cryolite.
(C) Cyanide ion is used as ligand for leaching of silver.
(D) Phosphine acts as a ligand in Wilkinson catalyst.
(E) The stability constants of $$Ca^{2+}$$ and $$Mg^{2+}$$ are similar with EDTA complexes.

We need to identify which statements are correct from (A) through (E).

Statement (A): Ethane-1,2-diamine is a chelating ligand. Ethane-1,2-diamine (ethylenediamine, en) is $$H_2N-CH_2-CH_2-NH_2$$. It has two nitrogen donor atoms that can simultaneously coordinate to the same metal ion, forming a five-membered chelate ring. This is TRUE.

Statement (B): Metallic aluminium is produced by electrolysis of aluminium oxide in the presence of cryolite. In the Hall-Heroult process, $$Al_2O_3$$ is dissolved in molten cryolite ($$Na_3AlF_6$$) to lower the melting point, and then electrolysed to produce metallic aluminium at the cathode. This is TRUE.

Statement (C): Cyanide ion is used as ligand for leaching of silver. In the MacArthur-Forrest process, silver (and gold) ores are leached using dilute sodium cyanide solution in the presence of air: $$4Ag + 8CN^- + 2H_2O + O_2 \rightarrow 4[Ag(CN)_2]^- + 4OH^-$$ The cyanide ion acts as a ligand forming the soluble dicyanoargentate(I) complex. This is TRUE.

Statement (D): Phosphine acts as a ligand in Wilkinson catalyst. Wilkinson's catalyst is $$[RhCl(PPh_3)_3]$$, where $$PPh_3$$ is triphenylphosphine, not phosphine ($$PH_3$$). Triphenylphosphine and phosphine are different compounds. The ligand is triphenylphosphine, not phosphine itself. This statement is FALSE.

Statement (E): The stability constants of $$Ca^{2+}$$ and $$Mg^{2+}$$ are similar with EDTA complexes. The stability constant (log K) of $$[Ca(EDTA)]^{2-}$$ is approximately 10.7, while that of $$[Mg(EDTA)]^{2-}$$ is approximately 8.7. These values differ significantly (by about 2 orders of magnitude). This is FALSE.

Statements (A), (B), and (C) are correct.

Answer: Option 3 — (A), (B), (C) only