Question

Which of the following salts will give highest pH in water?
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AIPMT 2014

• A. $NaCl$
• B. $KCl$
• C. $CuS{O}_4$
• D. $N{a}_{2}C{O}_3$

Answer 1

The correct option is D $N{a}_{2}C{O}_3$

$NaCl$ and $KCl$ are the salts of a strong acid and strong base. They do not undergo hydrolysis. Their aqueous solutions are neutral.

Since, cupric hydroxide is a weak base and sulphuric acid is a strong acid so, hydrogen ion is more than hydroxyl ion in water and as result of this, the aqueous solution of copper sulphate is acidic in nature.

$N{a}_{2}C{O}_3$ is basic due to hydrolysis of $C{O}_3^{2-}$ ion.
$C{O}_3^{2-}+H_{2}O\rightleftharpoons HC{O}_3^{-}+O{H}^{-}$

Hence, $N{a}_{2}C{O}_3$ will give highest pH in water.

Hence, option (c) is correct answer.