Why does dry HCl gas not change the colour of dry litmus paper?
- AHCl gas acts as a dehydrating agent.
- BBlue litmus becomes dry in the presence of dry HCl gas.
- CNo H3O+ ions are present. Litmus changes colour only in the presence of H3O+ ions.
- DMore than one of the above
- ENone of the above
Show answer and explanation
Correct answer: (c) No H3O+ ions are present. Litmus changes colour only in the presence of H3O+ ions.
Explanation
Litmus changes colour only in the presence of H3O+ ions, produced when an acid dissociates in water.
Dry HCl gas cannot dissociate without water, so no H3O+ ions form and dry litmus stays unchanged.