Answer :
Let's suppose the formula is
CoCl2.nH2O
CoCl2.nH2O−> CoCl2 + nH2O
H2O has the mss= 15.8-9.32 = 6.48g
H2O contains moles= 6.48/(1.0x2+16.0) = 0.36
Moles in CoCl2 = 9.32/(58.9+35.5x2) = 0.071747
n = 0.36/0.071747
= 5
CoCl2.nH2O
CoCl2.nH2O−> CoCl2 + nH2O
H2O has the mss= 15.8-9.32 = 6.48g
H2O contains moles= 6.48/(1.0x2+16.0) = 0.36
Moles in CoCl2 = 9.32/(58.9+35.5x2) = 0.071747
n = 0.36/0.071747
= 5