Q.Give the reactions supporting basic nature of ammonia.

Step 1. Reaction with water. Section 9.8.3: NH3(g) + H2O(l) is in equilibrium with NH4+(aq) + OH-(aq) — the OH- ions produced make aqueous ammonia basic.

Step 2. Reaction with acids. Ammonia neutralises acids to form ammonium salts: NH3 + HCl → NH4Cl; 2NH3 + H2SO4 → (NH4)2SO4 — a basic substance reacting with an acid to form a salt is itself evidence of basicity.

Step 3. Precipitating metal hydroxides. Aqueous ammonia precipitates the hydroxides (or hydrated oxides) of metals from their salt solutions, e.g. ZnSO4(aq) + 2NH4OH(aq) → Zn(OH)2(s, white precipitate) + (NH4)2SO4(aq), and FeCl3(aq) + 3NH4OH(aq) → Fe(OH)3(s) (the text describes this as a hydrated iron oxide) + 3NH4Cl(aq) — precipitating a metal HYDROXIDE is itself only possi …

Collecting the three reaction classes given under 'basic nature' in section 9 …

• Citing ammonia's complex-formation reactions (with Cu2+ or Ag+, Exercise 14) as evidence of basicity; those reactions demonstrate ammonia's Lewis-base/ligand character via its lone pair, which is related but distinct from the Bronsted basic …