Which statement about a weak base’s ionisation is true?

• A. Between 8 and 11
• B. Exactly 14
• C. Completely ionises
• D. Between 0 and 7

Answer: (A)

Weak bases in water do not fully ionise; they establish an equilibrium between the undissociated base and the ions it produces. This means the solution is alkaline but not extremely so. The pH of a weak base solution is typically greater than 7 but not extremely high, often falling in the range around 8 to 11 depending on how strong the base is and its concentration. That’s why the statement describing ionisation as giving a pH between 8 and 11 is the best fit. The other possibilities describe conditions that are either acidic (between 0 and 7) or require full, not partial, ionisation (which would be true for strong bases, not weak ones, and would push the pH toward 14).