What will be the action of the following substances on litmus paper? Dry HCl gas, moistened NH3 gas, lemon juice, carbonated soft drink, curd, soap solution.
Dry HCl gas: No action Moistened NH3 gas: Turns red litmus blue. Lemon juice: Turns blue litmus red. Carbonated soft drink: Turns blue litmus red. Curd: Turns blue litmus red. Soap solution: Turns red litmus blue. Explanation: Dry HCl gas does not liberate hydrogen ion, hence no action takes place with litmus paper. NH3 gas forms ammonium hydroxide with water which turns red litmus paper blue. Lemon juice is citric acid, so it turns blue litmus paper red. Carbonate soft drink contains carbon dioxide dissolved in water. Carbon dioxide forms carbonic acid with water; which turns blue litmus paper red. Curd contains lactic acid and hence turns blue litmus paper red. Soap solution is basic in nature hence it turns red litmus paper blue.
