Question

When the prefix cyclo- comes before the name of a hydrocarbon, what does it mean?

Answer 1

It means the beginning and the end of the alkane-chain are connected.

Explanation:

Cyclo-propane forms a triangle:

Cyclo-pentane does something similar:

I think you get the idea from here.

Note :
Because of the 'ends' connecting, the cyclo-alkanes are of the form `C_nH_(2n)` in stead of `C_nH_(2n+2)`, and thus isomeres of the mono-alkenes.