If $[H_3O^+]$ of a solution is $1 \times 10^{-4} \text{ M}$, what is the value of $pOH$ at $298 \text{ K}$?

If $20 \ mL$ of an acidic solution of $pH$ $3$ is diluted to $100 \ mL$,the $H^{+}$ ion concentration will be

What is the $pH$ of the solution containing $1.342 \times 10^{-3} \ M \ H^{+}$ ions?
$(\log 1.342 = 0.1277)$

The $pH$ of milk,black coffee,tomato juice,lemon juice and egg white are $6.8, 5.0, 4.2, 2.2$ and $7.8$ respectively. Calculate the corresponding hydrogen ion concentration $[H^+]$ in each.

What will be the sum of $pH$ and $pOH$ in an aqueous solution?

Observe the following solutions:
$I$. Black coffee
$II$. $0.2 \ M \ NaOH$
$III$. Lemon juice
$IV$. Lime water
$V$. Human saliva
$VI$. Tomato juice
The number of solutions having $pH$ range of $1-7$ and $7-14$,in the above list,is respectively.