When romeo kisses juliet the first time, does she kiss back?
defend your answer with evidence from the play and answer in complete sentences.

Well, there's no evidence for that one way or the other. Since there are no stage directions like "(Juliet kisses him back)", how Juliet receives that kiss would be up to the director. 

I tend to think she received the first one passively. Romeo said "Move not, while my prayer's effect I take," and she was new to kissing, so she probably moved not.

Dogs and cat