Which statement about acids and litmus is true?

Which statement about acids and litmus is true?

• A. Acids turn red litmus blue.
• B. Acids turn blue litmus red.
• C. Acids are neutral on the pH scale.
• D. Bases turn blue litmus red.

Answer: (B)

Litmus indicator reveals acidity by changing color with hydrogen ion activity. In acidic solutions, the blue form of litmus turns red; in basic solutions, red litmus turns blue. Therefore, acids turn blue litmus red. The other statements mix up the color changes or misstate pH behavior: acids are not neutral on the pH scale, and bases cause the opposite color change with litmus.

Litmus indicator reveals acidity by changing color with hydrogen ion activity. In acidic solutions, the blue form of litmus turns red; in basic solutions, red litmus turns blue. Therefore, acids turn blue litmus red. The other statements mix up the color changes or misstate pH behavior: acids are not neutral on the pH scale, and bases cause the opposite color change with litmus.