Question

$HCl$ gas does not effect a dry strip of blue litmus paper but it turns red in the presence of a drop of water ?

• A. Blue litmus paper in the presence of water accepts the proton from $HCl$ and turns blue to red
• B. Blue litmus paper in the presence of water accepts the chloride ion from $HCl$ and turns blue to red
• C. Blue litmus paper in the presence of water with acid do not turn into red
• D. None of the above

Answer 1

The correct option is A Blue litmus paper in the presence of water accepts the proton from $HCl$ and turns blue to red

A dry litmus paper will not show any effect in the presence of dry HCl due to the absence of $H^{+}$ ions, whereas on putting a drop of water, the blue litmus paper immediately turns to red due to the presence of $H^{+}$ ions as $HCl$ turns in aqueous form and give $H^{+}$ in presence of water.

Hence, option A is correct.