Explain why thick white fumes are formed when a glass rod dipped in NH₄OH is brought near the mouth of a bottle full of HCl gas.

Explain why dry hydrogen chloride gas does not affect a dry strip of blue litmus paper, but it turns red in the presence of a drop of water.

Explain why dilute hydrochloric acid cannot be concentrated by boiling beyond 22.2%.

Give reason for the following : Hydrogen chloride gas cannot be dried over quick lime.