The $pH$ of an aqueous solution containing $[H^{+}] = 3 \times 10^{-3} \ M$ is

$40 \, mg$ of pure sodium hydroxide is dissolved in $10 \, L$ of distilled water. The $pH$ of the solution is

In a solution of $pH = 5$,more acid is added in order to reduce the $pH$ to $2$. The increase in hydrogen ion concentration is $......$ times.

An aqueous solution of $HCl$ with $pH \ 1.0$ is diluted by adding an equal volume of water (ignoring the dissociation of water). The $pH$ of the $HCl$ solution would be (Given $\log 2 = 0.30$):

$1 \, mL$ of $0.1 \, M$ $HCl$ is added to $999 \, mL$ of $0.1 \, N$ $NaCl$ solution. The $pH$ of the resulting solution will be:

An alkaline solution of $Mg(OH)_2$ has $pH = 12$. What amount of $Mg(OH)_2$ (in $gm$) is dissolved in $200 \ mL$ of the final solution?