Which statement correctly describes a strong base in comparison with a weak base?

• A. A strong base completely ionises to form OH- ions, while a weak base only partially ionises.
• B. A strong base does not ionise, while a weak base does.
• C. Both forms do not ionise in water.
• D. A strong base produces water directly without ions.

Answer: (A)

In aqueous solutions, how strong a base is depends on how completely it ionizes to form hydroxide ions. A strong base, such as sodium hydroxide, dissociates fully in water to give Na+ and OH−, so the concentration of OH− is high and the solution is strongly alkaline. A weak base, like ammonia, only partially ionizes in water; it exists in equilibrium between its un ionized form and the ionized form that produces some OH−, so the OH− concentration is lower and the solution is less basic. This difference in ionization explains why a strong base has a higher pH and greater conductivity than a weak base. The idea that a base doesn’t ionize at all or that it produces water directly without ions isn’t how bases behave in water—the key distinction is complete versus partial ionization to form hydroxide ions.