Piperidine is essential in drug production. It is a weak organic base. 

C₅H₁₀NH + H₂O ⇌ C₅H₁₀NH₂⁺ + OH^–

 What is the K_b for piperidine if 0.067 M solution of piperidine has a pH of 11.94?

• A. 8.7×10^–3
• B. 1.1×10^–12
• C. 1.3×10^–3
• D. 2.0×10^–23

Answer: (C)