`10^(-6)M` NaOH is diluted to 100 times. The pH of the diluted base is

Options

A. between 5 and 6
B. between 6 and 7
C. between 10 and 11
D. between 7 and 8

Answer

D

Explanation

`[OH^(-)]` of `10^(-6)` M NaOH `=10^(-6)`
when 100 times diluted
`[OH^(-)]=(10^(-6))/(10^(2))=10^(-8)`
As it is a weak base, autoprotolysis of water will also take place. So, the contributaioin of `OH^(-)` ions from water must also be considered.
`:.` Total `[OH^(-)]=10^(-8)+[OH^(-)]_("water")`