1. She cut it open.

Question

(Is 'open' an objective complement? What is the part of speech of 'open'? Is 'open' an adjective or a 'verb'?)

2. Chocolate is made from cocoa beans.
3. Chocolate is made from cacao beans.
(Which one is correct?)

4. He is picking up a cocoa pod with his hand.

5. He is picking up a cacao pod with his hand.

(Which one is correct?)

6. Cocoa trees grow in rain forest countries.

7. Cacao trees grow in rain forest countries.
(Which one is correct?)

Answer 1

1 ~~ In this sentence, "open" is an object complement. It's an adjective modifying the direct object "it."
http://grammar.ccc.commnet.edu/grammar/objects.htm#objects
Scroll down to the COMPLEMENTS section and read the second example given for Object Complements. This is the same construction.

2-7 ~~ At first, I would have told you they are just two words for the same thing, but I have learned they are not!

http://www.ehow.com/info_8721957_difference-cacao-vs-cocoa-powder.html

http://vegetarian.about.com/od/beverage1/a/Difference-Between-Cocoa-And-Cacao.htm

So ... I'd use "cacao" when referring to the plant from which the beans come, and I'd use "cocoa" when referring to the beans and the chocolate powder or chocolate drink made from those beans..