At $25^{\circ} C$,the ${H_3}{O^+}$ concentration of a solution is $1.0 \times 10^{-10} \ M$. What is the $pOH$ value of the solution (in $.0$)?

At $25 \, ^\circ C$,the ionic product of water $(K_w)$ is equal to .......

At $45 \, ^oC$,the $pK_w$ of a neutral solution is $13.36$. The $pH$ of the solution will be .....

If $[H^{+}]$ ion concentration of a solution is increased by $10$ times,its $pH$ will be:

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 with $pH$ less than $7$ is

Calculate the concentration of $H_3O^{+}$ ion if the $pH$ of the solution is $2.8$.