Molecular mass of Na2CO3.10H2O is 286u .
Molecular mass of anhydrate Na2CO3 is 106u .
Difference in mass 286u−106u=180u
Percentage decrease =DiffernceOriginal×100
⇒% decrease=180286×100=62.9%
The formula of soda ash is (a) Na2CO3.10H2O (b) Na2CO3.2H2O (c) Na2CO3.H2O (d) Na2CO3