"Dry HCl is not acid". How do you prove it?

Explanation

1) Take about 1.0 gm of solid N/ACl in a clean and dry test tube.
2) Add some concentrated sulphuric acid to the test tube.
3) We observe a gas is evolved.
4) The reaction is`2N/ACl+H_2SO_4to2HCLuparrow+N/A_2SO_4` .
5) Test the gas evolved successively with dry and wet blue litmus paper.
6) We observe that there is no change in the colour of dry litmus paper, because dry HCL is not an acid. But HCL aqueous solution is an arid because wet blue litmus paper turned into red.
The HC l gas evolved at delivery tube dissociates in presence of water to produce hydrogen ions. In the absence of water dissociation of HCl molecules do not occur.
7) The dissocia tion of HCl in water is shown below.
`HCl+H_2OtoH_3O^(+)+Cl^-`
Hence acids give `H_3O^+` ions in water.