Are these the correct skeletal formulas for all structural isomers of C5H10?

[dwight87]

Homework Statement

Draw the skeletal formula for all of the structural isomers of C5H10

Homework Equations

The Attempt at a Solution

I attached a picture of what I got so far. Are they right and am I missing any. Thanks a lot.

I know that there should be another line coming from the corner of the square. My mistake.

 

[chemisttree]

Explain the difference between 11 and 7.

 

[dwight87]

They are exactly the same. Thanks for pointing that out. But are the rest right? Thanks again.