When a salt is treated with sodium hydroxide solution it gives gas X. On passing gas X through reagent Y a brown coloured precipitate is formed. X and Y respectively, are
- X = NH3 and Y = HgO
- X = NH4Cl and Y = KOH
- X = NH3 and Y = K2HgI4 + KOH
- X = HCl and Y = NH4Cl
Answer
(3) X = NH3 and Y = K2HgI4 + KOH
Solution
An ammonium salt with NaOH liberates ammonia:
NH4Cl + NaOH NaCl + NH3 + H2O X = NH3
NH3 passed through Nessler's reagent (alkaline K2HgI4) gives a brown precipitate (iodide of Millon's base):
2K2HgI4 + NH3 + 3KOH HgO Hg(NH2)I + 7KI + 2H2O
Y = K2HgI4 + KOH
Answer: (3)