Q. Buffer solutions have constant acidity and alkalinity because:
A) they have fixed value of pH
B) these give unionised acid or base on reaction with added acid or alkali
C) acids and alkalies in these solutions are shielded from attack by other ions
D) they have large excess of H+ or OH– ions
Explanation
[Solution from source] A buffer contains a weak acid with its conjugate base (or a weak base with its conjugate acid). Added H⁺ or OH⁻ is consumed to form the weakly ionised acid or base, so [H⁺] changes very little. A buffer's pH is not fixed absolutely (it depends on the ratio of components), and it does not hold a large excess of H⁺ or OH⁻. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.