During sodium extract preparation for Lassignd test both \(\mathrm{N}\) and \(\mathrm{S}\) present in organic compoud change to (a) \(\mathrm{NaCN}\) and \(\mathrm{Na}_{2} \mathrm{~S}\) (b) \(\mathrm{NaNH}_{2}\) and \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) (c) \(\mathrm{NaSCN}\) (d) \(\mathrm{NaNO}_{3}\) and \(\mathrm{Na}_{2} \mathrm{~S}\).

When studying organic compounds, which consist largely of carbon and hydrogen, the identification of other elements present is essential for understanding their structure and properties. Qualitative analysis is the cornerstone of this process. It includes various tests to detect the presence of elements beyond carbon and hydrogen, such as nitrogen, sulfur, halogens, and more.

The Lassaigne's test is a classic procedure in qualitative organic analysis. By heating an organic compound with sodium or sodium-potassium alloy, the test allows for the detection of various elements through the formation of soluble sodium salts. These salts can then be further analyzed to confirm the presence of specific elements. This traditional method is particularly useful because it's cost-effective and does not require sophisticated instruments.

Nitrogen and sulfur are commonly found in various functional groups in organic compounds. Identifying the presence of these elements is crucial for deducing the compound's structure. Lassaigne's test facilitates this by transforming nitrogen and sulfur into sodium cyanide (NaCN) and sodium sulfide (Na₂S) respectively.

These compounds are then subjected to specific chemical reactions to confirm their presence. For instance, sodium cyanide can be detected using Prussian blue formation, while for sodium sulfide, the use of lead acetate paper is common, which turns black upon contact with hydrogen sulfide gas released from the sodium sulfide. The detection methods rely on color changes or precipitate formation, making it simple to observe and confirm the presence of these elements.

The sodium fusion test, also known as the Lassaigne's test, is a critical part of the qualitative analysis toolkit in organic chemistry. It begins with the fusion of the sample with metallic sodium in a fusion tube. This high-temperature reaction helps in breaking down the complex organic molecules and facilitates the bond formation between the element in question and sodium.

Post fusion, the resultant cool mixture is then dissolved in water, leading to the formation of sodium salts that are soluble and can be tested further. For validation of nitrogen or sulfur, the content is treated with iron(II) sulfate and sulfuric acid for nitrogen, and with nitroprusside for sulfur. These are strong confirmatory tests: a positive result for nitrogen leads to the formation of a deep blue complex, while a purple or violet solution indicates the presence of sulfur.