When a nitrate is warmed with zinc powder and an NaOH solution, a gas is evolved. Which of the follo — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Step 1: Warming a nitrate with zinc powder and sodium hydroxide (NaOH) reduces nitrate ions to evolve ammonia gas (NH3). Step 2: Ammonia gas reacts with Nessler's reagent (alkaline K2[HgI4] solution) to form a basic mercuric amidonitrate complex, which appears as a brown precipitate. Step 3: Consequently, Nessler's reagent is turned brown by the evolved gas, matching option (c).