Verified Solution • 2025–26 Session moderate

QJEEM24Chcec4: JEE Main 2024 Chemistry - Class 11 JEEM24Chcec4 Solution: Lassaigne's test is used for detection of :

Lassaigne's test is used for detection of :

Multiple Choice Options

  • A Phosphorous and halogens only
  • B Nitrogen, Sulphur and Phosphorous only
  • C Nitrogen, Sulphur, phosphorous and halogens
  • D Nitrogen and Sulphur only

Step-by-Step Verified Solution

Lassaigne's test is a qualitative test in analytical chemistry used to detect the presence of certain elements, namely nitrogen, sulfur, and halogens in an organic compound. The test involves heating the organic compound with sodium metal to convert these elements to sodium salts, which can then react with specific reagents to yield visibly identifiable compounds.

Let's go through the options one by one:

Option A suggests that Lassaigne's test is used for the detection of phosphorous and halogens only. This is incorrect because the test is also used to detect nitrogen and sulfur.

Option B suggests that the test is for nitrogen, sulfur, and phosphorous only. However, Lassaigne's test does not typically involve a specific test for phosphorous.

Option C, which is the correct answer, indicates that this test is used to detect nitrogen, sulfur, phosphorous, and halogens. Even though phosphorous detection isn't as common as the detection of nitrogen, sulfur, and halogens in the typical Lassaigne's test, the option stating all four elements should be considered the most complete answer among those provided, given its inclusion of all elements that could potentially be detected with adaptations of the test.

Option D states that the test is for nitrogen and sulfur only, which is not entirely accurate because the test can also be used to detect halogens, and potentially, albeit less commonly, phosphorous.

Therefore, the most accurate answer is Option C: Nitrogen, Sulphur, phosphorous, and halogens.

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