8. Describe the molecular geometry around theC=Cdoublebondinanalkene.WhatistheHCHbondangle in ethene?

9. Butene (C4H8) has one C=C double bond in its structure. Draw structures for three possible structural isomers of butene.

10. The structural formula for 2-butene can be abbreviated CH3CH=CHCH3. Because of the lack of free rotation about the C=C double bond (see Question 9), there are two possible structures for this compound. Build models and draw structural formulas for two three-dimensional structures of 2-butene.