Google search ajax api limit?

I'm using php to get search from google, and I have few qustions

1. is there a limit of queries per day ?
2. is there a limit of queries per minute ?
3. if the limit is reached开发者_Python百科, what is the response code I'll be getting from google? Is it a json response - same as good response or is it 404/400 header?

Thanks for answering questions.

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I'd suggest checking the documentation:

http://code.google.com/apis/ajaxsearch/documentation/