In Lassaigne's test for nitrogen, the brilliant Prussian blue coloration is due to the formation of — Practical Organic Chemistry and Purification Chemistry Question

💡 Solution & Explanation

Cyanide ions react with $Fe^{2+}$ to form hexacyanoferrate(II), which then reacts with $Fe^{3+}$ to yield Iron(III) hexacyanoferrate(II), $Fe_4[Fe(CN)_6]_3$.