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

The $pH$ of an aqueous solution of $CH_3COONa$ of concentration $C \ M$ is given by:

Which of the following produce an alkaline solution when dissolved in water?
$(i)$ Borax
$(ii)$ Potash alum
$(iii)$ $Na_2CO_3$
$(iv)$ $NH_4NO_3$

$NH_4CN$ is a salt of a weak acid $HCN$ $(K_a = 6.2 \times 10^{-10})$ and a weak base $NH_4OH$ $(K_b = 1.8 \times 10^{-5})$. $A$ $1 \ M$ solution of $NH_4CN$ will be:

The solution of $Na_2CO_3$ has $pH$:

$A$ $100 \ mL$,$0.1 \ M$ solution of ammonium acetate is diluted by adding $100 \ mL$ of water. The pH of the resulting solution will be ($pK_{a}$ of acetic acid is nearly equal to $pK_{b}$ of $NH_{4}OH$)