If the pH of a Ca(OH)2 solution is measured as 9.0, what is the concentration of the Ca(OH)2 solution?

1 × 10-5 M

1 × 10-9 M

1 × 10-8 M

1 × 10-6 M

Convert pH to pOH.

Convert pOH to OH
Then since there are two mols OH ions in 1 mol Ca(OH)2, convert mols OH to mols Ca(OH)2.