When sodium chloride is dissolved in water,the sodium ion undergoes ........

The $pH$ of water is $7$ at $25^{\circ} C$. If water is heated to $80^{\circ} C$,its $pH$ will:

Given that $K_w$ for water is $10^{-13} \ M^2$ at $62 \ ^\circ C$,compute the sum of $pOH$ and $pH$ for a neutral aqueous solution at $62 \ ^\circ C$.

What will be the hydrogen ion concentration in moles $L^{-1}$ of a solution whose $pH$ is $4.58$?

The $pH$ of a solution is $5.0$. To this solution,sufficient acid is added to decrease the $pH$ to $2.0$. The increase in hydrogen ion concentration is $...$ times.

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