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.
In Earth Sciences. The calendar shows Spring beginning on the Equinox of either March  20 or September 22/23 in the Southern Hemisphere.    The traditional winter months are December-Janâ¦uary-February and the  spring months as March-April-May, for the Northern Hemisphere.