Which of the following statements about pH and H+ ion concentration is incorrect?
(a) Addition of one drop of concentrated HCl in NH4OH solution decreases pH of the solution.
(b) A solution of the mixture of one equivalent of each of CH3COOH and NaOH has a pH of 7
(c) pH of pure neutral water is not zero
(d) A cold and concentrated H2SO4 has lower H+ ion concentration than a dilute solution of H2SO4
Correct answer: (b) A solution of the mixture of one equivalent of each of CH3COOH and NaOH has a pH of 7
Explanation:
CH3COOH is weak acid while NaOH is strong base, so one equivalent of NaOH can not be neutralized with one equivalent of CH3COOH. Hence the solution of one equivalent of each does not have pH value as 7. Its pH will be towards basic side as NaOH is a strong base hence conc. of OH- will be more than the conc. of H+.