Question

Given below are two statements:
Statement I: In Lassaigne's test, the covalent organic molecules are transformed into ionic compounds.
Statement II: The sodium fusion extract of an organic compound having N and S gives prussian blue colour with FeSO4 and Na4[Fe(CN)6].
In the light of the above statements, choose the correct answer from the options given below.

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is false but Statement II is true
• D. Statement I is true but Statement II is false

Hint:

In Lassaigne's test, the presence of nitrogen and sulfur in an organic compound is tested by forming cyanide and thiocyanate ions after fusion with sodium. Prussian blue formation is specific to compounds containing nitrogen in the form of cyanides.

Answer 1

The Correct Option is D

Statement I: In Lassaigne's test, the covalent organic molecules are transformed into ionic compounds. This statement is true. Lassaigne's test involves fusing the organic compound with sodium metal. The covalent bonds in the compound break down, forming ionic sodium salts, which are soluble in water and can be easily tested for the presence of elements such as nitrogen (N), sulfur (S), and halogens.

Statement II: The sodium fusion extract of an organic compound having N and S gives prussian blue colour with FeSO4 and Na4[Fe(CN)6]. This statement is false. The correct reaction that leads to the formation of a prussian blue color indicates the presence of nitrogen alone. When both nitrogen and sulfur are present in the sodium fusion extract, it does not lead to the formation of prussian blue with FeSO4 and Na4[Fe(CN)6]. Instead, it would produce thiocyanate, which does not give a prussian blue color but a red coloration after further reaction with an acidic iron(III) solution.

Conclusion: Statement I is true but Statement II is false.