Red litmus paper is a type of indicator paper that is used to test the acidity or alkalinity of a solution. It is made from a water-soluble dye that is extracted from lichens.

When red litmus paper is dipped in a basic solution, it undergoes a color change from red to blue. This is due to the chemical reaction that occurs between the basic solution and the dye on the litmus paper.

Explanation:
- Basic solutions have a pH greater than 7. They contain a higher concentration of hydroxide ions (OH-) compared to hydrogen ions (H+).
- The dye on the red litmus paper is a weak acid. It has a red color in its acidic form and a blue color in its basic form.
- When the red litmus paper is dipped in a basic solution, the hydroxide ions from the solution react with the acidic dye on the paper.
- This reaction causes the dye to lose a hydrogen ion (H+) and gain a hydroxide ion (OH-).
- As a result, the dye molecule is converted into its basic form, which has a blue color.
- This color change is visible on the litmus paper, indicating that the solution is basic.

Importance of red litmus paper:
- Red litmus paper is a widely used indicator in chemistry labs and in various industries.
- It is a simple and inexpensive way to determine whether a solution is acidic or basic.
- The color change of red litmus paper when dipped in a basic solution provides a visual indication of the solution's pH.
- It helps in identifying the nature of a solution and is an important tool for conducting experiments and tests.

In conclusion, when red litmus paper is dipped in a basic solution, it changes color from red to blue. This color change is due to the reaction between the basic solution and the acidic dye on the litmus paper. It is a useful indicator to determine the pH of a solution and plays an important role in various scientific applications.