When both red and blue litmus paper are placed in the same solution and show no color change, what does this indicate?

When both red and blue litmus paper are exposed to the same solution and exhibit no color change, it indicates a neutral solution. Red litmus paper turns blue in basic or alkaline solutions and remains red in acidic solutions, while blue litmus paper turns red in acidic solutions and stays blue in basic or alkaline solutions. If neither paper changes color, it signifies that the solution is neither acidic nor basic, thus confirming it is neutral.

This understanding is rooted in the principles of acid-base chemistry, where neutral substances (with a pH of around 7) do not affect the litmus paper's color. Solutions that are acidic would change the blue litmus red, and basic solutions would change the red litmus blue, so the absence of any color change is pivotal in determining the neutrality of the solution.