Question

Given below are two statements:
Statement I: In ‘Lassaigne’s Test’, when both nitrogen and sulphur are present in an organic compound, sodium thiocyanate is formed.
Statement II: If both nitrogen and sulphur are present in an organic compound, then the excess of
sodium used in sodium fusion will decompose the sodium thiocyanate formed to give NaCN and Na₂S.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement I and Statement II are correct.
• B. Both Statement I and Statement II are incorrect.
• C. Statement I is correct but Statement II is incorrect.
• D. Statement I is incorrect but Statement II is correct.

Answer 1

The Correct Option is A

To solve this question, let's examine each statement regarding the Lassaigne's test:

1. Statement I: In Lassaigne’s Test, when both nitrogen and sulphur are present in an organic compound, sodium thiocyanate is formed.
   • Lassaigne’s Test involves the preparation of sodium fusion extract (by heating the organic compound with sodium) and then conducting various tests on the extract.
   • If the organic compound contains both nitrogen (\(N\)) and sulphur (\(S\)), they react with the sodium to form sodium thiocyanate (\(\text{NaSCN}\)).
   • This reaction is essential for the detection of both these elements simultaneously in the compound.
2. Statement II: If both nitrogen and sulphur are present in an organic compound, then the excess of sodium used in sodium fusion will decompose the sodium thiocyanate formed to give \(\text{NaCN}\) and \(\text{Na}_2\text{S}\).
   • This statement is based on the chemical reactions involved in Lassaigne’s Test whereby sodium thiocyanate can decompose further in the presence of excess sodium.
   • The decomposition reaction occurs as follows: \(\text{NaSCN + 2Na} \rightarrow \text{NaCN + Na}_{2}\text{S}\).
   • Hence, the formation of sodium cyanide (\(\text{NaCN}\)) and sodium sulfide (\(Na_{2}S\)) is possible under such conditions.

Therefore, both Statement I and Statement II are correct, which aligns with the given correct answer: "Both Statement I and Statement II are correct."