Chemistry - Salt Analysis Question with Solution | TestHub

The acidic radical (A) is iodide ($I^{-}$) because it reacts with AgNO₃ to form AgI (D), a yellow precipitate insoluble in ammonia. When $I^{-}$ reacts with HgCl₂, it forms HgI₂ (B), which is a scarlet red precipitate at room temperature. Upon heating to 400 K, HgI₂ undergoes a phase transition from its red tetragonal form to a yellow orthorhombic solid (C). Therefore, (C) is HgI₂, making Option (B) the correct answer.