Which of the following descries a solution that contain a buffer? A. Sodium hydroxide, a base, is added to the solution, and the pH of the solution becomes higher. B. Citric acid is added to the solution, but the pH of the solution does not change. C. Acetic acid is added to the solution, and the pH of the solution becomes lower. D. Distilled water is added to the solution, and the pH of the solution does not change.

B. Citric acid is added to the solution, but the pH of the solution does not change.

Explanation:

In chemistry, buffer solutions or simply called Buffer are solutions that resist a change in pH when an acid or base is added to them i.e they maintain a constant pH. This is as a result of the content of the solution. A buffer may contain a weak acid and its conjugate base (salt) or a weak base and its conjugate acid.

Hence, when a strong base or acid is added to them, they still restore the original pH of the solution due to the reaction that removes or neutralizes the hydrogen or hydroxide ions from the acid and base added to them respectively. This is what happens when Citric acid is added to the solution, but the pH of the solution does not change.

Citric acid, which is an acid, does not practically increase or decrease the pH of the solution. Hence, the solution is called a buffer.

the answer for apex is "1 and 6"