In universal indicators, red colour shows a pH of-

In a universal indicator, the red color shows a pH of 0 to 3, meaning the substance is strongly acidic. A universal indicator helps us understand how acidic or basic a substance is by changing color. It's a mix of different indicators that show various colors depending on the pH level. For example, a neutral solution turns green, an acidic solution turns yellow, orange, or red, and a basic solution turns blue, purple, or violet, with the exact color depending on the pH value.