Which statement about litmus paper is true for bases in aqueous solution?

Which statement about litmus paper is true for bases in aqueous solution?

• A. Turns blue litmus red
• B. No color change
• C. Turns red litmus blue
• D. Turns litmus purple

Answer: (C)

Litmus paper acts as a simple acid–base indicator. Its color changes with pH: in acidic solutions blue litmus turns red, while in basic (alkaline) solutions red litmus turns blue. Bases raise pH and reduce hydrogen ion concentration, so the red dye flips to blue. That’s why bases in water make red litmus paper blue. Blue litmus stays blue under basic conditions, and there’s a color change rather than no change.

Litmus paper acts as a simple acid–base indicator. Its color changes with pH: in acidic solutions blue litmus turns red, while in basic (alkaline) solutions red litmus turns blue. Bases raise pH and reduce hydrogen ion concentration, so the red dye flips to blue. That’s why bases in water make red litmus paper blue. Blue litmus stays blue under basic conditions, and there’s a color change rather than no change.