Yes, blue litmus paper turns red in acidic solution, and red litmus paper turns blue in basic solution.

Introduction:
Indicators are substances that undergo a color change when they are exposed to acidic or basic solutions. They are commonly used in chemistry to determine the pH (acidity or basicity) of a solution.

Acids and Indicators:
Acids are substances that release hydrogen ions (H+) when dissolved in water, while bases release hydroxide ions (OH-). Indicators can detect the presence of these ions, causing a color change in the solution. However, not all indicators respond to acids in the same way.

Universal Indicator:
Universal indicator is a mixture of several indicators that can detect a wide range of pH values. It changes color according to the pH of the solution it is added to. In the presence of acids, universal indicator turns red or orange, indicating a low pH (below 7). The exact color change depends on the strength and concentration of the acid.

Other Acid-Base Indicators:
Apart from universal indicator, there are several other indicators that change color in the presence of acids. Some examples include:

1. Litmus paper: It turns red in the presence of acids and blue in the presence of bases.
2. Phenolphthalein: It is colorless in acidic solutions and turns pink in basic solutions.
3. Methyl orange: It is red in acidic solutions and yellow in basic solutions.
4. Bromothymol blue: It changes from yellow in acidic solutions to blue in basic solutions.

These indicators work through a phenomenon called ionization. They have different chemical structures that respond to specific ions, causing a color change. Acidic solutions provide hydrogen ions (H+), which interact with the indicator molecules and alter their structure, resulting in a color change.

Bases and Indicators:
Similar to acids, bases also cause color changes in indicators. However, the color changes are opposite to those caused by acids. For example, litmus paper turns blue in the presence of bases, while phenolphthalein turns pink. The exact color change depends on the strength and concentration of the base.

Conclusion:
In conclusion, both acids and bases can change the color of indicators. Acids usually cause indicators to turn red, orange, or yellow, depending on the specific indicator and the pH of the solution. Bases, on the other hand, cause indicators to turn blue, green, or pink. The specific color change depends on the chemical structure of the indicator and the pH of the solution. By observing the color change, one can determine the approximate pH of the solution, making indicators a valuable tool in chemistry.