How can you distinguish between chlorine and sodium chloride?

• A. Add litmus paper; chlorine bleaches it, sodium chloride does nothing.
• B. Add red cabbage dye.
• C. Heat to see color change.
• D. Add ammonia to turn blue.

Answer: (A)

Chlorine is a bleaching agent, especially in damp form, so it destroys the color of litmus paper. Sodium chloride is a neutral salt and doesn’t bleach litmus, so the paper stays its original color. Testing with damp litmus will show a loss of color for chlorine but no change for sodium chloride, making this the clear way to tell them apart. The other ideas rely on indirect indicators or reactions that aren’t as reliable or direct for this distinction.