#### Answer

The molecular formula is $C_4H_{5}N$.
For the lewis structure: Draw a carbon wherever two lines meet and, a line begins and ends. Draw the two lines as double bond. And then add the number of hydrogens so that each carbon has four bonds.

#### Work Step by Step

1) Draw a carbon wherever two lines meet and, a line begins and ends.
2) Draw N where N is given and a lone pairs on N. Also draw a H bonded to N.
3) Then add the number of hydrogens so that each carbon has four bonds.
4) Count the number of C, H and O. In this structure there are 4 Carbons, 5 hydrogens and 1 Nitrogen. Thus, the molecular formula is $C_4H_{5}N$.