Which of the following compounds is not expected to show Lassaignes' test for nitrogen?

Lassaignes' test for nitrogen involves fusing the organic compound with sodium metal. This fusion converts any nitrogen present into sodium cyanide (NaCN). The fused mass is then extracted with water, and the extract is tested by adding ferrous sulfate, ferric chloride, and acidifying with dilute sulfuric acid. If nitrogen is present, a Prussian blue precipitate forms. For nitrogen to be detected, it must be bonded to carbon in the compound so that during fusion, it can form cyanide ion (CN⁻).

Now, let's evaluate each option:

Option A: Propanenitrile (CH₃CH₂CN)

Propanenitrile contains a nitrile group (-C≡N), where nitrogen is bonded to carbon. During sodium fusion, the nitrile group is reduced to cyanide ion. Thus, it will give a positive Lassaignes' test for nitrogen.

Option B: Hydroxylamine hydrochloride (NH₂OH·HCl)

Hydroxylamine hydrochloride has the formula NH₂OH·HCl. The nitrogen atom is bonded to hydrogen and oxygen but not to carbon. During sodium fusion, nitrogen cannot form cyanide ion because cyanide requires nitrogen to be bonded to carbon. Instead, it may decompose to form ammonia or other nitrogen compounds that do not yield cyanide. Therefore, it will not give a positive Lassaignes' test for nitrogen.

Option C: Nitromethane (CH₃NO₂)

Nitromethane contains a nitro group (-NO₂), where nitrogen is bonded to carbon and oxygen atoms. During sodium fusion, the nitro group is reduced to cyanide ion. Thus, it will give a positive Lassaignes' test for nitrogen.

Option D: Ethanamine (CH₃CH₂NH₂)

Ethanamine is an amine where nitrogen is bonded to carbon atoms. During sodium fusion, amines are converted to cyanide ion. Thus, it will give a positive Lassaignes' test for nitrogen.

Hence, hydroxylamine hydrochloride (Option B) is not expected to show Lassaignes' test for nitrogen because its nitrogen is not bonded to carbon, preventing cyanide formation.

So, the answer is Option B.