MESA Entrance Practice Exam 2026 - Free MESA Practice Questions and Study Guide

On the pH scale, 7 is the balance point between acidity and basicity. The pH of a solution is the negative logarithm of the hydrogen ion concentration, so neutral solutions have equal amounts of hydrogen ions and hydroxide ions. For water at room temperature, that balance corresponds to [H+] about 1 × 10^-7 M, giving a pH of 7. Values below 7 mean more H+ and a shift toward acidity, while values above 7 mean more OH- and a shift toward basicity. So the statement that a neutral solution has a pH of 7 is true. The other descriptions—acidic, strongly acidic, or basic—don’t fit because they imply pH values on the wrong side of 7.