The pH of a 0.001 M aqueous solution of sodium hydroxide will be:

The pH of a solution is determined by the negative logarithm (base 10) of the concentration of hydrogen ions (H+). For a solution of sodium hydroxide (NaOH), a strong base, it dissociates completely in water to form sodium ions (Na+) and hydroxide ions (OH-).

The concentration of OH- ions in the solution is 0.001 M.

We can use the ion product of water (Kw) which is 1.0 x 10^-14 at 25 degrees Celsius to find the concentration of H+ ions.

Kw = [H+][OH-]

We can rearrange this equation to solve for [H+]:

[H+] = Kw / [OH-]

Substituting the given values:

[H+] = 1.0 x 10^-14 / 0.001 = 1.0 x 10^-11 M

Now, we can find the pOH of the solution using the formula:

pOH = -log10 [OH-]

pOH = -log10 (0.001) = 3

Since pH + pOH = 14, we can find the pH by subtracting the pOH from 14:

pH = 14 - pOH = 14 - 3 = 11

So, the pH of a 0.001 M aqueous solution of sodium hydroxide is 11.