HAZMAT Technician Practice Exam

Which of the following is a true statement about acids?

1. They have a pH greater than 7

2. They turn blue litmus red

3. They form bases when mixed with water

4. They are always corrosive

The correct answer is: They turn blue litmus red

The statement that acids turn blue litmus red is accurate. This characteristic is a fundamental property used to identify acidic substances. When an acid is present, it donates protons (H⁺ ions) to the solution, which causes a shift in color on the litmus paper due to the specific chemical reactions taking place. The other statements do not hold true in the same context. For instance, acids have a pH less than 7, not greater. They do not form bases when mixed with water; instead, they dissociate to release hydrogen ions, which can help to establish an acidic environment. While many acids can be corrosive, not all acids exhibit corrosive properties under normal conditions. Therefore, the only definitive statement regarding acids from the provided options is that they turn blue litmus red.