12. A hydrocarbon has a molecular weight of approximately 60 and contains 17.2% hydrogen. What is the molecular formula of the hydrocarbon? Write all of the structural isomers that have this formula.

13. A hydrocarbon has a molecular weight of 56.0 and contains 85.7% carbon. What is its molecular formula? What structural and geometric isomers could it have?

14. Write equations for the reactions of 1-pentene with each of the following reagents:
(a) Br2
(b) H2SO4
(c) HI
(d) HOCI
(e) H2 and Ni

In each case, show the structure of the product organic molecule.