The acidic nature of an aqueous solution of $FeCl_3$ is due to:

Arrange the aqueous solutions of the following salts in the increasing order of $pH$: $CuSO_4$ $(I)$,$NaCN$ $(II)$,$KCl$ $(III)$.

The $pH$ of an aqueous solution of $CH_3COONH_4$ is found to be $6.7$ at $25\,^{\circ}C$. The concentration of the $CH_3COONH_4$ solution is ($K_a$ for $CH_3COOH = 1.0 \times 10^{-5}$ and $pK_b$ for $NH_4OH = 4.4$)

An aqueous solution of sodium carbonate is alkaline because sodium carbonate is a salt of

An aqueous solution of $K_2SO_4$ will be ....

It is found that at $25\,\text{°C}$,$0.1\,M$ solutions of four sodium salts $NaA$,$NaB$,$NaC$,and $NaD$ have the $pH$ values $7$,$9$,$10$,and $11$ respectively. Which one of the corresponding acids is the strongest?