$pH$ of an aqueous solution of $NH_4Cl$ is

Which of the following aqueous solutions will have the highest $pH$?

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?

Which one of the following substances will be a mixed salt?

The aqueous solution of $AlCl_3$ is acidic due to the hydrolysis of

The $pH$ of an aqueous solution of alum is ....