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Which statement is wrong about pH and $H^+$
A
pH of neutral water is not zero
B
Adding 1 N solutions of $CH_3COOH$ and NaOH (equal volumes), pH will be seven
C
pH of dilute and hot $H_2SO_4$ is more than concentrated and cold $H_2SO_4$
D
Mixing solution of $CH_3COOH$ and HCl, pH will be less than 7
Detailed Solution
Neutral water has pH 7 at 25 °C, not zero; true.
Equal amounts of acetic acid (weak acid) and NaOH (strong base) give sodium acetate. The acetate ion hydrolyses ($CH_3COO^- + H_2O \rightleftharpoons CH_3COOH + OH^-$), so the solution is basic with pH greater than 7, not 7. So this statement is wrong.
Dilute acid has lower $[H^+]$ than concentrated acid, so its pH is higher; true.
A mixture of two acids is acidic, pH less than 7; true.
So the wrong statement is that mixing 1 N $CH_3COOH$ and 1 N NaOH gives pH seven.
Equal amounts of acetic acid (weak acid) and NaOH (strong base) give sodium acetate. The acetate ion hydrolyses ($CH_3COO^- + H_2O \rightleftharpoons CH_3COOH + OH^-$), so the solution is basic with pH greater than 7, not 7. So this statement is wrong.
Dilute acid has lower $[H^+]$ than concentrated acid, so its pH is higher; true.
A mixture of two acids is acidic, pH less than 7; true.
So the wrong statement is that mixing 1 N $CH_3COOH$ and 1 N NaOH gives pH seven.