The correct answer is C. Phenolphthalein.
When sodium carbonate is mixed with sulfuric acid, a neutralization reaction occurs. This reaction is a type of chemical reaction in which an acid and a base react to form a salt and water. In this case, the salt formed is sodium sulfate.
The pH of a solution is a measure of its acidity or alkalinity. A pH of 7 is neutral. A pH below 7 is acidic, and a pH above 7 is alkaline.
The pH of a solution can be changed by adding an acid or a base. When an acid is added to a solution, the pH decreases. When a base is added to a solution, the pH increases.
Phenolphthalein is an indicator that changes color depending on the pH of the solution. It is colorless in acidic solutions and pink in basic solutions.
When sodium carbonate is mixed with sulfuric acid, the pH of the solution will decrease. This is because sulfuric acid is a strong acid. As the pH decreases, the phenolphthalein will change color from colorless to pink.
Therefore, phenolphthalein is a suitable indicator when solution of sodium carbonate is mixed with sulfuric acid.
The other options are not suitable indicators for this reaction. Methylene blue is a blue dye that changes color from blue to colorless in acidic solutions. Methyl red is a red dye that changes color from red to yellow in acidic solutions. Methyl orange is an orange dye that changes color from orange to yellow in acidic solutions.
These dyes would not be suitable indicators for
this reaction because they would not change color until the pH of the solution was very acidic.