On the pH scale, which values indicate acids, bases, and neutral solutions, and what color would universal indicator show for a strong acid?

• A. Acids pH < 7, bases pH > 7, neutral pH = 7; a strong acid would turn the universal indicator blue.
• B. Acids pH < 7, bases pH > 7, neutral pH = 7; a strong acid would turn the universal indicator green.
• C. Acids pH < 7, bases pH > 7, neutral pH = 7; a strong acid would turn the universal indicator yellow.
• D. Acids pH < 7, bases pH > 7, neutral pH = 7; a strong acid would turn the universal indicator red.

Answer: (D)

Understanding how pH works is key. Acids have pH values below 7, neutral solutions sit at pH 7, and bases (alkalines) have pH values above 7. A universal indicator is designed to show a range of colors that correspond to different pH levels: strong acids appear red, neutral solutions appear green, and bases shift toward blue (and purple for very strong bases). So for a strong acid, the universal indicator would turn red.