The notation  hydrated compound ânH2O , where n is the number of water molecules per formula unit of the salt, is commonly used to show that a salt is hydrated. The n is usually a low integer, though it is possible for fractional values to occur. For example, in a monohydrate n is one, and in a hexahydrate n is 6.
When does spring start? How you define the first day of spring depends on whether you follow the astronomical or meteorological seasons. This year, spring will take place between March 20 and June 21, if you use the astronomical method. But it starts slightly earlier, between March 1 and May 31, if you follow the meteorological calendar.
Spring Swarmers: How to Prepare for Termite Season. Spring Swarmers: How to Prepare for Termite Season. The first official day of spring is Sunday, March 20th (the earliest arrival of spring of our lifetime so far in the Northern Hemisphere, according the the Old Farmerâs Almanac). This is also the first official day of termite season!