$H^{+}$ is a

Determine the order of basic strength for the following compounds:
$(I)$ $CH_3COO^-$
$(II)$ $CH_3CH_2^-$
$(III)$ $NH_2^-$
$(IV)$ $C_6H_5O^-$

The pair of compounds which cannot exist together in aqueous solution is:
$I.$ $NaH_2PO_4$ and $NaHCO_3$
$II.$ $Na_2CO_3$ and $NaHCO_3$
$III.$ $NaOH$ and $NaH_2PO_2$
$IV.$ $NaHCO_3$ and $NaOH$

The concentration of which ion is decreased when $NH_3$ solution is added?

Derive $K_w = K_a \times K_b$ and $pK_w = pK_a + pK_b$ for a weak base $B$ and its conjugate acid $BH^{+}$.

Which of the following is not a conjugate acid-base pair?