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.
Much of the country is in the grip of icy winter weather but according to the Meteorological Office spring is here. It classes the first day of spring as 1 March, saying March, April and May are regarded as the spring months. But traditionally spring has started on the night of 20/21 March and a row has erupted over the official date. You would not regard the first three weeks of June as spring, yet historically summer does not start until 21 June, says a spokesman for the Met Office. Equally, the bulk of people now regard 1 March as the first day of spring. Bloom