In order of increasing percent water content:CoCl₂.6H₂O, Ba(OH)₂.8H₂O, MgSO₄.7H₂O
[tex]\tt \%element=\dfrac{Ar~element}{MW~compound}\times 100\%[/tex]
CoCl₂.6H₂O.MW=237.90 g/mol
6H₂O MW = 6.18=108 g/mol
[tex]\tt \%H_2O=\dfrac{108}{237.9}\times 100\%=45.4\%[/tex]
MgSO₄.7H₂O.MW=246.48 g/mol
MW 7H₂O = 7.18=126 g/mol
[tex]\tt \%H_2O=\dfrac{126}{246.48}\times 100\%=51.1\%[/tex]
Ba(OH)₂.8H₂O MW=315.48 g/mol
MW 8H₂O = 8.18=144 g/mol
[tex]\tt \%H_2O=\dfrac{144}{315.48}\times 100\%=45.6\%[/tex]