Which term describes a measure of the acidity of a solution?

• A. Buffer Solution
• B. pH
• C. pOH
• D. Titration

Answer: (B)

The measure of how acidic a solution is centers on the hydrogen ion concentration and how that translates into a single value on the pH scale. pH is defined as the negative logarithm of [H+], so even small changes in hydrogen ion concentration produce noticeable shifts in pH. A lower pH means higher acidity because there are more free H+ ions, while a higher pH indicates lower acidity (more basic). Neutral conditions occur around pH 7 at room temperature. The other terms describe different ideas: a buffer solution is about maintaining pH rather than giving a measurement; pOH relates to hydroxide ion concentration and connects to pH via pH + pOH = 14 at 25°C; titration is a method to determine concentration or to find an endpoint, not a direct measure of acidity.