State the number of water molecules present in crystal of washing soda and plaster of paris. What are these water molecules called as?

Explanation

`*` Washing soda crystals contain 10 molecules of water `(Na_(2)Co_(3).10H_(2)O)`
`*` Plaster of Paris crystals contain `1//2` molecule of water`(CaSO_(4)" . "(1)/(2)H_(2)Oor2CaSO_(4)" . "H_(2)O)`.
`*` These molecules of water are called water of crystals.