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Which of the following statements about universal indicator is/are true ? 1. It is a mixture of several indicators. 2. It shows different colours at different concentrations of hydrogen ions in solution. 3. It helps to determine the strength of given acid and base in titration. Select the correct answer using the code given below :
Explanation
A universal indicator is a pH indicator composed of a mixture of several compounds (such as phenolphthalein, methyl red, and bromothymol blue) that exhibit smooth color changes over a wide range of pH values [1]. It shows different colors at different concentrations of hydrogen ions in a solution, ranging from red for strong acids (high H+ concentration) to violet for strong bases [1]. While it can compare the relative strengths of acids and bases by indicating their approximate pH, it is generally not used to determine the precise strength or equivalence point in a titration [1]. In titrations, specific indicators like phenolphthalein or methyl orange are preferred because they provide a sharp, distinct color change at the rapid pH shift near the equivalence point, whereas universal indicators change color gradually across the entire pH scale.
Sources
- [1] https://en.wikipedia.org/wiki/Universal_indicator