What color does acid turn blue litmus paper?

What color does acid turn blue litmus paper?

• A. Red
• B. Blue
• C. Purple
• D. Green

Answer: (A)

Litmus paper is a simple indicator of acidity. Blue litmus paper changes color from blue to red in acidic solutions because the presence of hydrogen ions shifts the dye to red under acidic conditions. So in an acidic environment, blue litmus paper turns red. The other colors don’t reflect acidity on blue litmus paper in this standard test—blue stays blue in neutral or basic conditions, and purple or green aren’t typical litmus responses for ordinary acids. Red is the correct color change you’d observe.

Litmus paper is a simple indicator of acidity. Blue litmus paper changes color from blue to red in acidic solutions because the presence of hydrogen ions shifts the dye to red under acidic conditions. So in an acidic environment, blue litmus paper turns red. The other colors don’t reflect acidity on blue litmus paper in this standard test—blue stays blue in neutral or basic conditions, and purple or green aren’t typical litmus responses for ordinary acids. Red is the correct color change you’d observe.