H2O (water) has 2 hydrogen atoms and 1 oxygen atom.
Solution :
Comparing the solubility of silver chromate for the solutions :
----- Less soluble than in pure water.
----- Less soluble than in pure water.
----- Similar solubility as in the pure water
----- Similar solubility as in the pure water
The silver chromate dissociates to form :
When 0.1 M of 
is added, the equilibrium shifts towards the reverse direction due to the common ion effect of 
, so the solubility of 
decreases.
Both 
and 
are neutral mediums, so they do not affect the solubility.
PH = -log([H+])
[H+] = 10^(-pH)
[H+] = 10^(-9)
[H+][OH-] = Kw
Kw = 1.0*10^-14 at 25 degrees celsius.
[OH-] = Kw/[H+] = (1.0*10^-14)/(1*10^-9) = 1.0*10^-5
The concentration of OH- ions is 1.0*10^-5 M.
