What does the hydrolysis of $AlCl_{3}$ produce?

Which of the following aqueous solutions of salts has $pH < 7$ at $298 \text{ K}$?

Which among the following salts turns red litmus blue in its aqueous solution?

The hydrolysis of sodium carbonate involves the reaction between

The $pK_a$ of a weak acid,benzoic acid and $pK_b$ of a weak base,ammonium hydroxide are $4.25$ and $4.75$ respectively. Then the $pH$ of $0.1 \ M$ solution of ammonium benzoate will be

Why is the $pH$ of an aqueous solution of copper sulphate less than $7$?