Which solution has the highest $pH$ value?

When $100 \ mL$ of $0.1 \ M$ $NaOH$ is added to $50 \ mL$ of $0.2 \ M$ $HCl$ at $25 \ ^oC$,the $pH$ of the resulting solution will be:

How many liters of water must be added to $1 \ L$ of an aqueous $HCl$ solution with $pH = 1$ to make the $pH$ of the resulting solution equal to $2$ (in $L$)?

Which of the following has a $pH$ of $12$?

Millimoles of calcium hydroxide required to produce $100 \ mL$ of the aqueous solution of $pH$ $12$ is $x \times 10^{-1}$. The value of $x$ is $..............$. (Nearest integer). Assume complete dissociation.

$x \ mg$ 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 $H_2O$)