Principles Related to Practical Chemistry: NEET previous year questions

NEET 2026 · the full paper

1. NEET 2026 · Q77

   In a test tube containing a salt, a few drops of dilute $H_2SO_4$ was added, which gave colourless vapours having the smell of vinegar. The vapours turned the blue litmus paper red. Identify the correct anion from the following:

   1. (1)

      Sulphide, $S^{2-}$

   2. (2)

      Sulphate, $SO_4^{2-}$

   3. (3)

      Acetate, $CH_3COO^-$

   4. (4)

      Carbonate, $CO_3^{2-}$

   Answer and solution

   Answer: (3)

   A colourless acidic vapour with the smell of vinegar indicates acetic acid: acetate salts react with dilute H$_{2}$SO$_{4}$ to liberate CH$_{3}$COOH (vinegar odour), which turns blue litmus red. Sulphide would give rotten-egg-smelling H$_{2}$S, carbonate gives odourless CO$_{2}$ (which turns lime water milky), and sulphate evolves no gas with dilute H$_{2}$SO$_{4}$.