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.
Earliest spring since 1896! The 2016 vernal or spring (or fall) equinox comes on March 20 at 4:30 UTC (March 19 at 11:30 p.m. CDT). The March equinox signals the beginning of spring in the Northern Hemisphere â earliest spring since 1896 â and autumn in the Southern Hemisphere. It marks that special moment when the sun crosses the celestial equator going from south to north. In 2016, this equinox arrives on March 20 at 4:30 UTC, or on March 19 at 11:30 p.m. Central Daylight Time. Hereâs what we in the Northern Hemisphere know about this equinox. Our sunrise is earlier now, and nightfall comes later. Plants are sprouting.