Question

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

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

Answer 1

Answer: (C)

The highest $pH$ refers to the basic solution containing $O{H}^{-}$ions. Therefore, the basic salt releasing more $O{H}^{-}$ions on hydrolysis will give highest $pH$ in water.
Only the salt of strong base and weak acid would release more $O{H}^{-}$ion on hydrolysis. Among the given salts, $N{a}_{2}C{O}_3$ corresponds to the basic salt as it is formed by the neutralisation of $NaOH$ [strong base] and $H_{2}C{O}_3$ [weak acid].
$C{O}_3^{2-}+H_{2}O\rightleftharpoons HC{O}_3^{-}+O{H}^{-}$