View the structrue such that `HOCH_(2)-C-CH_(2)CH_(3)` is aligned vertically with `(-CH_(2)OH)` and `(C_(2)H_(5))` groups extending away from the viewer. Replace the Wedge-Dash bonds by striaght lines to get the Fischer projection formula.
b. Proceed in the similar way as in (a)
c. Proceed in the similar way as in (a).
d. View the structrue such that
`(OHC-C-C CH_(2)OH)` is aligned vertically with the `(-CO)` and `(-CH_(2)OH)` group extending away from the observer. Place the `(-CHO)` group at the top.
