Question

why a bottle of liquor ammonia is dipped into water for some hours before being opened.

Answer 1

At room temperature the vapor pressure of Liquid ammonia is too high , so if we open at room temperature it evaporate quickly  hence to avoid such situation we usually put liquid ammonia bottle in water to cool down . Cooling will help to decrease the vapor pressure of ammonia to bring down . it won't let help to evaporate fast  .