Q. Which ion is responsible for the basicity of a solution when ammonia is dissolved in water?
✅ Correct Answer: (B)
OH-
Explanation: When ammonia dissolves in water it reacts partially: NH3 + H2O ⇌ NH4+ + OH-. The OH- ion increases the pH, making the solution basic. NH4+ is the conjugate acid and its presence does not make the solution basic (it is slightly acidic). NH2- (amide) is not formed in aqueous ammonia under normal conditions. H+ would make solution acidic, not basic.
Explanation by: Sikhar Chaudhary
When ammonia dissolves in water it reacts partially: NH3 + H2O ⇌ NH4+ + OH-. The OH- ion increases the pH, making the solution basic. NH4+ is the conjugate acid and its presence does not make the solution basic (it is slightly acidic). NH2- (amide) is not formed in aqueous ammonia under normal conditions. H+ would make solution acidic, not basic.