Answer:

Explanation:
Expanded Structure shows all the atoms and the bonds of the molecule. It is important to remember, each Carbon molecule have four bonds, while the Hydrogen just one. So:
1)
Pentene. 5 Carbon molecules, 10 Hydrogen molecules. It's an isomer, so this organic compound has multiple arrangements.
2) 
Ethane. 2 Carbon and 6 Hydrogen Molecules. Check it below.
You add solute until it can't dissolve anymore.