What happens to litmus paper when placed in sodium sulfate solution?

• A. No change.
• B. Turns red.
• C. Turns blue.
• D. Discolors.

Answer: (A)

Litmus paper changes color only in acidic or basic solutions. Sodium sulfate formed from a strong acid and a strong base gives a solution that is essentially neutral, around pH 7. In a neutral solution, litmus paper does not change color, so there is no visible change (blue stays blue, red stays red).