Equilibrium constants are given (in atm) for the following reactions at `0^@C`
(a) `SrCl_2.6H_2O(s) iff SrCl_2.2H_2O(s) + 4H_2.O(g), K_p = 6.89 xx 10^(-12)`
(b) `Na_2HPO_4.12H_2O(s) iff Na_2HPO_4. 7H_2O(s) +5H_2O(g), K_p = 5.25 xx 10^(-13)`
(c) `Na_2SO_4. 10 H_2O(s) iff Na_2SO_4(s) + 10H_2O(g), K_p = 4.08 xx 10^(-25)`
The vapour pressure of water at `0^@C` is 4.58 torr.
Calculate the pressure of water vapour in equilibrium at `0^@C` with each of (a), (b) and (c)