What is the percentage of water of crystallisation in a pure sample of washing soda (Na_(2)CO_(3).10 H_(2)O) ?

What is the percentage of water of crystallisation in a pure sample of

1.	What is the percentage of water of crystallisation in a pure sample of washing soda (Na_(2)CO_(3).10 H_(2)O) ?
Answer» Solution :Molecular mass of `Na_(2)CO_(3).10H_(2)O=46+12+48+180=286.0u` PERCENTAGE of WATER of CRYSTALLISATION `= ((180u))/((286u))xx100=62.94%`.