KCET 2026 Chemistry Solved Paper

Concept:Bromide salts give characteristic reddish brown bromine gas with concentrated $\mathrm{H}_{2}\mathrm{SO}_{4}$ and form a pale yellow precipitate of $\mathrm{AgBr}$ with silver nitrate.Explanation:When a bromide salt $\mathrm{BA}$ is heated with concentrated $\mathrm{H}_{2}\mathrm{SO}_{4}$, hydrogen bromide is formed first.$$\mathrm{BA} + \mathrm{H}_{2}\mathrm{SO}_{4} \rightarrow \mathrm{BHSO}_{4} + \mathrm{HBr}$$The $\mathrm{HBr}$ produced reduces sulfuric acid and is oxidised to bromine gas.$$2\mathrm{HBr} + \mathrm{H}_{2}\mathrm{SO}_{4} \rightarrow \mathrm{Br}_{2} + \mathrm{SO}_{2} + 2\mathrm{H}_{2}\mathrm{O}$$Bromine vapours, $\mathrm{Br}_{2}$, are reddish brown in colour, matching the observation.In aqueous solution, the bromide ion reacts with silver nitrate to give silver bromide.$$\mathrm{Ag}^{+} + \mathrm{Br}^{-} \rightarrow \mathrm{AgBr} \downarrow$$Silver bromide is a pale yellow precipitate.Hence, the anion $\mathrm{A}^{-}$ in the salt is $\mathrm{Br}^{-}$.Answer:$\mathrm{Br}^{-}$ (Option D)