$\begin{array}{*{20}{c}}
{CHO} \\
| \\
{HCOH} \\
| \\
{HOCH} \\
| \\
{HCOH} \\
| \\
{C{H_2}OH} \\
I
\end{array}\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$\begin{array}{*{20}{c}}
{CHO} \\
| \\
{HCOH} \\
| \\
{HCOH} \\
| \\
{HOCH} \\
| \\
{C{H_2}OH} \\
{II}
\end{array}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$\begin{array}{*{20}{c}}
{CHO} \\
| \\
{HCOH} \\
| \\
{HCOH} \\
| \\
{HCOH} \\
| \\
{C{H_2}OH} \\
{III}
\end{array}$
$\begin{align}
\begin{matrix}
C{{H}_{3}}-CH-C{{O}_{2}}H \\
|\,\,\,\,\,\,\,\, \\
\underset{\oplus }{\mathop{N}}{{H}_{3}} \\
\end{matrix}\,\,\,\,\,\,p{{K}_{a}}=2.2 \\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,p{{K}_{b}}=4.4 \\
\end{align}$