Which of the following statements about $\mathrm{pH}$ and $\mathrm{H}^{+}$ ion concentration is incorrect?
Which of the following statements about $\mathrm{pH}$ and $\mathrm{H}^{+}$ ion concentration is incorrect?
Addition of one drop of concentrated $\mathrm{HCl}$ in $\mathrm{NH}_{4} \mathrm{OH}$ solution decreases $\mathrm{pH}$ of the solution.
A solution of the mixture of one equivalent of each of $\mathrm{CH}_{3} \mathrm{COOH}$ and $\mathrm{NaOH}$ has a $\mathrm{pH}$ of 7
$\mathrm{pH}$ of pure neutral water is not zero
A cold and concentrated $\mathrm{H}_{2} \mathrm{SO}_{4}$ has lower $\mathrm{H}^{+}$ ion concentration than a dilute solution of $\mathrm{H}_{2} \mathrm{SO}_{4}$
Solution
$\mathrm{CH}_{3} \mathrm{COOH}$ is weak acid while $\mathrm{NaOH}$ is strong base, so one equivalent of $\mathrm{NaOH}$ can not be neutralized with one equivalent of $\mathrm{CH}_{3} \mathrm{COOH}$. Hence the solution of one equivalent of each does not have $\mathrm{pH}$ value as 7 . Its $\mathrm{pH}$ will be towards basic side as $\mathrm{NaOH}$ is a strong base hence conc. of $\mathrm{OH}$ will be more than the conc. of $\mathrm{H}^{+}$
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