Question

why does dry HCL gas not change the colour of the dry litmus paper?
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Answer 1

Answer:

In case of dry HCl gas, there is no presence of water and so, the dye on litmus paper cannot react with the gas. So, any dry gas will not give any change in the colour of litmus paper.

Answer 2

Answer:

Dry HCL it does not dissociate to give H

+

ions. Acids dissociate to give ions only in the aqueous solution. In this, HCL is not in the aqueous form nor the litmus paper is wet, so the colour of the litmus paper does not change.