An organic compound containing both nitrogen and sulphur is fused with an excess of sodium metal to prepare Lassaigne's extract. Which of the following ionic species will be predominantly present in the resulting extract for detection?

Step-by-step solution

Normally, when an organic compound containing both nitrogen and sulphur is fused with sodium, sodium thiocyanate ( NaSCN ) is formed, which provides the thiocyanate ion ( SCN ⁻ ). However, when an excess of sodium metal is used during the fusion process, the sodium thiocyanate decomposes to form sodium cyanide and sodium sulphide. NaSCN + 2 Na NaCN + Na ₂ S As a result, the extract will predominantly contain cyanide ( CN ⁻ ) and sulphide ( S ²⁻ ) ions instead of thiocyanate ions. Answer: Cyanide ( CN ⁻ ) and Sulphi