Five solutions A, B, C, D and E when tested with universal indicator showed pH as 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 in increasing order of hydrogen-ion concentration.

Explanation

A solution having pH equal to 7 is neutral. A solution with pH range 0 - 7 is acidic while a solution with pH range 7 – 14 is basic.
Smaller the value of pH in the range 0 – 7, stronger is the acid. Higher the value of pH in range 7 - 14, stronger is the base (alkali).
Based on above, we can decide the acidic or basic nature of A, B, C, D and E:

The pH in increasing order of hydrogen ion concentration are :