Answer
The molecular formula is $C_5H_{10}O$.
For the lewis structure: Draw a carbon wherever two lines meet and, a line begins and ends. 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 O where O is given and two lone pairs on O.
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 5 Carbons, 10 hydrogens and 1 Oxygen. Thus, the molecular formula is $C_5H_{10}O$.
