Ammonia Weak Base Equilibrium

Steps:

• Ammonia reacts with water to form NH₄⁺ and OH⁻, indicating base behavior by producing hydroxide ions.
• The reversible reaction shows incomplete dissociation, confirming ammonia as a weak base.
• OH⁻ production increases pH above 7, so statement 2 is false.
• Adding OH⁻ shifts equilibrium left per Le Chatelier's principle, favoring NH₃ production, so statement 3 is true.

Why B is correct:

• B selects statements 1 and 3, aligning with the definition of a weak base (partial OH⁻ production) and Le Chatelier's principle for equilibrium shifts.

Why the others are wrong:

• A includes incorrect statement 2 (pH >7, not 7).
• C omits correct statement 3 on equilibrium shift.
• D includes incorrect statement 2 and omits correct statement 1.

Final answer: B