Correct Answer - C
`Ca(OH)_(2)hArrCa^(2+) + 2 OH^(-)`
`K_(sp)=[Ca^(2+)][OH^(-)]^(2)=5.5xx10^(-6)` (Given)
`:.s(2s)^(2)=5.5xx10^(-6)`
or `4s^(3)=5.5xx10^(-6) ` or `s^(3)=1.375xx10^(-6)`
`:. S=1.11xx10^(-2)M`
`:. [OH^(-)]=2s=2.22xx10^(-2)M`
`:.pOH=-log(2.22xx10^(-2))=2-0.3464=1.65`
`:.pH=14-1.65=12.35`