At `25^(@)C`, the dissociation constant of a base BOH is `1.0xx10^(-12)`. The concentration of hydroxyl ions in 0.01 M aqueous solution of base would be :

Options

A. `1.0xx10^(-5) mol L^(-1)`
B. `1.0xx10^(-6)mol L^(-1)`
C. `2.0xx10^(-6)mol L^(-1)`
D. `1.0xx10^(-7)mol L^(-1)`

Answer

D

Explanation

`K_(b)=1.0xx10^(-12)`
`[BOH]=0.01 M`
`{:(,BOH,hArr,B^(+),+,OH^(-)),("Initial",1,,0,,0),("conc.",,,,,),("At equal.",(1-x),,Cx,,Cx):}`
`K_(b)=((Cx)xx(Cx))/(C(1-x))=(Cx^(2))/(1-x)=1.0xx10^(-12)`
or `(0.01x^(2))/(1)=1.0xx10^(-12)(1-x ~~ 1)`
`x = 1.0xx10^(-7)mol L^(-1)`