You can get more info about the exams by visiting College Board CLEP site
For free sample questions visit these sites:
Prepping for the Exam
There are several online resources that allow you to learn or review material for a CLEP exam. A large volume of free academic content is available at the Khan Academy website.
Those preparing for a CLEP test may also consider using iTunes U to access a variety of course content. The iTunes U app is available for iphone, ipod touch, and ipad. iTunes U content is also available via the iTunes software for PC or Mac.