GED Science Practice

Which term refers to a water-soluble compound capable of turning litmus blue and reacting with an acid to form a salt and water?

1. Autotroph

2. Auxin

3. Base

4. Bacteria

The correct answer is: Base

The term that describes a water-soluble compound capable of turning litmus paper blue and reacting with an acid to form a salt and water is known as a base. In chemistry, bases are substances that can accept protons (H+) or donate electron pairs, which is why they increase the pH level of a solution, turning litmus paper from red to blue. When a base combines with an acid in a reaction known as neutralization, it results in the formation of a salt and water. This is a fundamental characteristic of bases and illustrates their role in acid-base chemistry. The ability to change the color of litmus paper is a common indicator used in laboratories to assess the acidity or basicity of a solution. Other terms provided do not fit this description. For example, autotrophs are organisms that produce their own food from inorganic substances, auxins are plant hormones, and bacteria are single-celled microorganisms. None of these options relate to the properties of bases and their reactions with acids. Therefore, the correct understanding of the behavior of bases is critical in distinguishing them from other scientific terms and concepts.