Which one of the following types of medicines is used for treating indigestion?

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.

Equal lengths of magnesium ribbons are taken in test tubes $A$ and $B$. Hydrochloric acid $(HCl)$ is added to test tube $A$,while acetic acid $(CH_3COOH)$ is added to test tube $B$. The amount and concentration taken for both the acids are the same. In which test tube will the fizzing occur more vigorously and why?

Why does an aqueous solution of an acid conduct electricity?

Do basic solutions also have $H^+_{(aq)}$ ions? If yes,then why are these basic?

What effect does the concentration of $H^+_{(aq)}$ ions have on the nature of the solution?