Answer 1-3, please.

1) For each system (cyclopentadiene + maleic anhydride) and (furan + maleic anhydride) which is more stable, endo or exo?

2) What is the structural and electronic difference between cyclopentadiene and furan?

3) Is maleic anhydride an electron rich or electron poor diene? (Hint: draw resonance structure(s) to assist you.)