Question

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

• A. The addition of one drop of conc HCl solution in $N{H}_{4}Cl$ solution decreases the pH of the solution.
• B. A solution of the mixture containing equal moles of each $C{H}_{3}COOH$ and NaOH has a pH of 7.
• C. The pH value depends on the concentration of $\left[H^{+}\right]$ ion
• D. A cold and concentrated $H_{2}S{O}_4$ has a lower $H^{+}$ ion concentration than a dilute solution of $H_{2}S{O}_4$.

Answer 1

The correct option is B A solution of the mixture containing equal moles of each $C{H}_{3}COOH$ and NaOH has a pH of 7.

We know that reaction of acid and base is a neutralisation reaction and the pH of the obtained solution is approximately equal to 7 only if either both acids and bases are strong or weak. Here, $C{H}_{3}COOH$ is a weak acid and NaOH is a strong base, this reaction does not yield the product whose pH is close to 7. Hence, this statement is wrong.