If the $pH$ of water is less than ......,the water pipes undergo corrosion.

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.

An aqueous solution tends to have a $p^H$ of $0$. Then the solution will be .....

What is the difference between the terms 'hydrolysis' and 'hydration'?

At a certain temperature $T$,if the conductivity of pure water is $5.5 \times 10^{-7} \ S \ cm^{-1}$,calculate the $pH$ of water at the given temperature. Given: $\lambda_{H^{+}}^\infty = 350 \ S \ cm^2 \ eq^{-1}$ and $\lambda_{OH^{-}}^\infty = 200 \ S \ cm^2 \ eq^{-1}$.

The unit of the ionic product of water $(K_W)$ is.......