AFOQT Practice Test

What does a buffer do?

1. Increases acidity

2. Prevents sudden changes in pH

3. Neutralizes a base only

4. Reduces hydroxide ion concentration

The correct answer is: Prevents sudden changes in pH

A buffer is a solution that helps maintain a relatively constant pH when small amounts of an acid or a base are added. It does this by either absorbing excess hydrogen ions or providing hydrogen ions when they are depleted, thereby preventing drastic changes in the acidity or alkalinity of the solution. Thus, the correct answer indicates that a buffer effectively prevents sudden changes in pH, which is its primary function and why the choice is correct. The other statements do not accurately capture the role of buffers. For instance, increasing acidity suggests an active shift in pH rather than stabilization. Neutralizing a base only suggests a limited functionality, whereas buffers can respond to both acids and bases. Reducing hydroxide ion concentration implies a focus solely on bases, missing the broader aspect of pH regulation that includes both acid and base reactions.