What is the $pH$ of a $1 \ mM$ solution of $NaOH$?

What will be the resultant $pH$ when $100 \ mL$ of an aqueous solution of $HCl$ $(pH = 2)$ is mixed with $200 \ mL$ of an aqueous solution of $NaOH$ $(pH = 12)$?

$4 \ g$ of $NaOH$ is added in water to form $500 \ mL$ solution at $298 \ K$. What is the $pH$ of the solution? (Molar mass of $NaOH = 40 \ g \ mol^{-1}$)

The $pH$ of a $0.005 \ M \ H_2SO_4$ solution will be:

Calculate the volume of $0.1 \ M \ NaOH$ required to complete the neutralization of $300 \ mL$ of $HCl$ solution having $pH = 2.25$. (in $mL$)

$x \ mg$ of $Mg(OH)_2$ (molar mass $= 58 \ g/mol$) is required to be dissolved in $1.0 \ L$ of water to produce a $pH$ of $10.0$ at $298 \ K$. The value of $x$ is $........... mg$ ($Nearest$ $integer$). ($Given$: $Mg(OH)_2$ is assumed to dissociate completely in $H_2O$)