Equilibrium - Result Question 55
####57. Which of the following statements about $pH$ and $H^{+}$ion concentration is incorrect? [2000]
(a) Addition of one drop of concentrated $HCl$ in $NH_4 OH$ solution decreases $pH$ of the solution.
(b) A solution of the mixture of one equivalent of each of $CH_3 COOH$ and $NaOH$ has a pH of 7
(c) $pH$ of pure neutral water is not zero
(d) A cold and concentrated $H_2 SO_4$ has lower $H^{+}$ion concentration than a dilute solution of $H_2 SO_4$
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Solution:
- (b) $CH_3 COOH$ is weak acid while $NaOH$ is strong base, so one equivalent of $NaOH$ can not be neutralized with one equivalent of $CH_3 COOH$. 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 $H^{+}$.
