Why does dry $HCl$ gas not change the colour of the dry litmus paper ?
Colour of the litmus paper is changed by the hydrogen ions. Dry $HCl$ gas does not contain $H ^{+}$ ions. It is only in the aqueous solution that an acid dissociates to give ions.
since in this case, neither $HCl$ is in the aqueous form nor the litmus paper is wet, therefore, the colour of the litmus paper does not change.
Why do acids not show acidic behaviour in the absence of water ?
Which one of the following types of medicines is used for treating indigestion ?
How is the concentration of hydroxide ions $(OH^-)$ affected when excess base is dissolved in a solution of sodium hydroxide ?
What is a neutralisation reaction? Give two examples.
Write word equations and then balanced equations for the reaction taking place when -
$(a)$ dilute sulphuric acid reacts with zinc granules.
$(b)$ dilute hydrochloric acid reacts with magnesium ribbon.