Question

Which of the following statements about $pH$ and $H^{+}$ ion concentration is incorrect?

• A. Addition of one drop of concentrated $HCl$ in $N{H}_{4}OH$ solution decreases pH of the solution
• B. A solution of the mixture of one equivalent of each of $C{H}_{3}COOH$ and NaOH has a pH of $7$
• C. pH of pure neutral water is not zero
• D. A cold and concentrated $H_{2}S{O}_4$ has lower $H^{+}$ ion concentration than a dilute solution of $H_{2}S{O}_4$

Answer 1

Answer: (B), (D)

$C{H}_{3}COOH$ is weak acid while $NaOH$ is strong base, so one equivalent of $NaOH$ cannot be neutralised with one equivalent of $C{H}_{3}COOH$. Hence, one equivalent of each does not have $pH$ value $7$. As the $NaOH$ is a strong base, the solution will be basic having a pH more than $7$ .
So, $H_2\times$ dibasic acid