Question

What will be the action of the following substances on litmus paper ?

• Hydrochloric acid
• Moistened ${\text{NH}}_3$ gas
• Lemon juice
• Carbonated soft drink
• Curd
• Soap solution

Answer 1

Effects on litmus paper:

• Hydrochloric acid: Blue litmus will turn red.
• Moistened ${\text{NH}}_3$ gas: Red litmus will turn blue.
• Lemon juice (contains citric acid): Blue litmus will turn red.
• Carbonated soft drinks (contains carbonic acid): Blue litmus will turn red.
• Curd (contains lactic acid): Blue litmus will turn red.
• Soap solution (basic): Red litmus will turn blue.