Mention the range of $pH$ value for identification of a base.

What happens to the $pH$ of a basic aqueous solution if the concentration of $[OH^-]$ ions increases?

Five solutions $A, B, C, D$ and $E$ when tested with universal indicator showed $pH$ values of $4, 1, 11, 7$ and $9$,respectively. Which solution is:
$(a)$ neutral?
$(b)$ strongly alkaline?
$(c)$ strongly acidic?
$(d)$ weakly acidic?
$(e)$ weakly alkaline?
Arrange the $pH$ values in increasing order of hydrogen-ion concentration.

On what basis are acids classified as strong and weak acids?

The $pH$ scale is applicable to which of the following?

Which of the following solutions is most basic?