Alanine is an amino acid that can have both equilibria in water: 
H₂N⎯CHCH₃⎯COOH + H₂O ⇌ ⁺H₃N⎯CHCH₃⎯COOH + OH^- K_b = 7.4x10⁻⁵H₂N⎯CHCH₃⎯COOH + H₂O ⇌ H₂N⎯CHCH₃⎯COO^- + H₃O⁺ K_a = 4.5×10⁻³
It forms a zwitterion by intramolecular proton transfer H₂N⎯CHCH₃⎯COOH ⇌ ⁺H₃N⎯CHCH₃⎯COO^-
Determine the equilibrium constant for the reaction using the given K_a and K_b values

• A. 60
• B. 3.3x10⁷
• C. 1.6x10^-2
• D. 3.3x10^-7

Answer: (B)