Which among the following stage is a suitable indicator when a solution of sodium carbonate is mixed with sulphuric acid?
(1) Methylene blue
(2) Methyl red
(3) Phenolphthaline
(4) Methyl orange
Answer: (4) Methyl orange is a pH indicator frequently used in titrations. It is often used in titrations because of its clear and distinct color change. Because it changes color at the pH of a mid-strength acid, it is usually used in titrations for acids. In a solution becoming less acidic, methyl orange moves from red to orange and finally to yellow, with the reverse occurring for a solution increasing in acidity. The entire color change occurs in acidic conditions. In an acid, it is reddish, and in an alkali, it is yellow.
