When sodium acetate is added to an acetic acid solution,the $pH$ of the solution will . . . . . . .

$A$ saturated solution of $BaSO_4$ at $25^\circ C$ is $4 \times 10^{-5} \ M$. The solubility of $BaSO_4$ in $0.1 \ M \ Na_2SO_4$ at this temperature will be:

The solubility of $AgCl$ is least in which of the following solutions?

Write about the common ion effect.

Given below are two statements:
Statement $I$: On passing $HCl_{(g)}$ through a saturated solution of $BaCl_2$,at room temperature white turbidity appears.
Statement $II$: When $HCl$ gas is passed through a saturated solution of $NaCl$,sodium chloride is precipitated due to common ion effect.
In the light of the above statements,choose the most appropriate answer from the options given below:

Test tubes $A$ and $B$ contain solutions of $NH_4Cl$ and $NaCl$ respectively. What happens if $Mg(OH)_2$ solution is added to both test tubes?