Provide the structures for the molecules below:

a. Ethanal (Acetaldehyde):
b. Hexanal:
c. Heptanal:
d. Benzaldehyde:
e. Propanone (Acetone):
f. 2-Butanone:
g. 2-Pentanone:
h. 3-Pentanone:
i. 4-Methyl-2-pentanone:
j. 4-Heptanone:
k. Cyclohexanone:
l. 2-Methyl-butanal: