Kaplan Nursing Entrance Practice Exam

A low pH indicates what type of ionic concentration?

1. Excess of hydroxide ions

2. Excess of hydrogen ions

3. Neutral ion concentration

4. Equal concentration of positive and negative ions

The correct answer is: Excess of hydrogen ions

A low pH is indicative of an acidic solution, which means that there is a higher concentration of hydrogen ions in the solution. The pH scale, which ranges from 0 to 14, measures the acidity or basicity of a solution. A pH value below 7 signifies that the solution is acidic. This acidity comes from the presence of a greater number of hydrogen ions compared to hydroxide ions. In contrast, higher pH values indicate basic solutions, where hydroxide ions are in excess compared to hydrogen ions. The concept of neutral ion concentration generally refers to a pH of exactly 7, where the concentrations of hydrogen and hydroxide ions are equal. Similarly, equal concentrations of positive and negative ions do not specifically correspond to low pH levels, as they can exist in various pH contexts. Thus, the presence of an excess of hydrogen ions is the key factor that defines a low pH.