What does blue litmus paper indicate when it shows no color change in a solution?

When blue litmus paper is used to test a solution and shows no color change, this indicates that the solution has a neutral pH, typically around 7. Blue litmus paper is designed to remain blue in basic solutions and change to red in acidic solutions. If there is no change in color, it means that the solution is neither acidic nor basic, confirming its neutrality.

In the context of pH, an acidic solution would turn blue litmus paper red, while a basic solution would keep it blue or possibly even turn red litmus paper blue. Neutralization refers to the process of an acid and a base reacting to form water and a salt, which does not apply here since no change occurs with the litmus paper. Thus, the presence of no color change confirms that the solution is neither acidic nor basic, reinforcing the idea that it has a neutral pH.