Question

Which one of the following compounds is soluble (will not precipitate) A. CuS B. AgS C. PbCl2 D. CuSO4 E. NH4Cl

Answer 1

Ans. Correct option. E NH₄Cl. NH₄Cl is a salt of strong acid (HCl) and weak base (NH₃). When dissolved in water, it completely dissociates into constituent ions (NH₄⁺ and Cl^-) and gets solvated. It exhibits very high solubility in water, around 383.0 g /L at room temperature.

# The sulfide ion (S^2-) is basic in nature. To solvate it, the solution must be acidic.

So, CuS and AgS are insoluble in water (but soluble in acidic solution).

# CuSO₄ is a salt of weak base (Cu(OH)₂) and strong acid (H₂SO₄). When dissolved in water, it completely dissociates into constituent ions and gets solvated. It exhibits very high solubility in water, around 200.0 g /L at room temperature.

Conclusion: Among the given options, CuSO₄ and NH₄Cl are highly soluble in water. Out of the two, NH4Cl exhibits highest solubility in water.

So, assuming equal mass of all the solutes being dissolved in neutral water, NH4Cl will be solvated maximum without precipitating before anyone solute.

So, correct option is- d. NH₄Cl