Question

which of the following compounds have electrovalent, covalent and co-ordinate bonds but do not have hydrogen bond:
a CaCl2. 2H2O
b..CuSO4.5H2O
c.FeSO4.7H2O
d Na2SO4.10H2O

Answer 1

Efflorescent substances are solids that can undergo spontaneous loss of water from hydrated salts.

Efflorescence occurs when the aqueous vapor pressure of the hydrate is greater than the partial pressure of the water vapor in the air

since loss of water takes place in these substances absence of Hydrogen bond (bond between H atom and highly electronegative atoms like N,O,F ) is noticed.

Na2SO4.10H2O and FeSO4.7H2O are efflorescence hydrates in the above mentioned question