Na_(2)CO_(3).10H_(2)O when exposed to air looses water of crystallisation and gives finally

Na_(2)CO_(3).10H_(2)O when exposed to air looses water of crystallisat

1.	Na_(2)CO_(3).10H_(2)O when exposed to air looses water of crystallisation and gives finally
Answer» `NaCO_(3). 4H_(2)O` `Na_(2)CO_(3). H_(2)O` `Na_(2)CO_(3). 7H_(2)O` `Na_(2)CO_(3). 9H_(2)O` ANSWER :B