You have four solutions A, B, C and D. The pH of solution A is 6, B is 9, C is 12 and D is 7.
(i) identify the most acidic and the most basic of the solutions.
(ii) Arrange the above four solutions in the increasing order of the H+ ion concentration.
(iii) State the change in colour of pH paper on dipping in solution C and D.

Explanation

(i) HCl will give rise to more `H^+` ions and `CH_3COOH` produces less `H^+` ions on dissociations. The colour of pH paper depends on the concentration of `H^+` ion. Colour becomes red for high `H^+` concentration.
(ii) (a) Most acidic- A most basic- C
(B) C,B,D,A/C `lt` B `lt` D `lt` A
(c ) In C blue in D green.