What is the effect of an alkali on litmus paper?

An alkali, which is a type of base, has the effect of turning litmus paper blue. Litmus paper is a pH indicator commonly used in chemistry to determine the acidity or basicity of a solution. In acidic solutions, litmus paper turns red, while in neutral or basic solutions, it remains unchanged or turns blue. When litmus paper comes into contact with an alkali, the pH of the solution is generally above 7, resulting in a color change to blue. This characteristic behavior of litmus paper makes it a useful tool for quickly testing the pH level of various solutions in both educational settings and practical applications.