To solve this problem, let's analyze each statement separately:$\newline$Statement I: Primary aliphatic amines react with $HNO_2$ to give unstable diazonium salts.$\newline$• Primary aliphatic amines react with nitrous acid $(HNO_2)$ to form aliphatic diazonium salts.$\newline$• These aliphatic diazonium salts are indeed unstable and decompose to form alcohols, nitrogen gas, and other products.$\newline$• Therefore, Statement I is correct.$\newline \newline$Statement II: Primary aromatic amines react with $HNO_2$ to form diazonium salts which are stable even above $300K. \newline$• Primary aromatic amines, such as aniline, react with nitrous acid to form aromatic diazonium salts.$\newline$• These aromatic diazonium salts are stable at low temperatures (around 273 K) but decompose at higher temperatures.$\newline$• They are not stable above 300 K, as they tend to decompose to form phenols and other products.$\newline$• Therefore, Statement II is incorrect.$\newline \newline$Analyzing the options:$\newline$• Option 1: Both Statement I and Statement II are correct. (Incorrect)$\newline$• Option 2: Both Statement I and Statement II are incorrect. (Incorrect)$\newline$• Option 3: Statement I is correct, but Statement II is incorrect. (Correct)$\newline$• Option 4: Statement I is incorrect, but Statement II is correct. (Incorrect)$\newline$Therefore, the correct option is Option 3.