This might rather fit in to stupid question category - but is there a tool that gu/estimates how much approximately could be paid for the click from the adsense ad?
https://adwords.google.com/select/KeywordToolExternal is the only thing that would be anywhere close to accurate, and even then I'd take it with a grain of salt.
Bare in mind that the KeywordTool shows how much Advertisers should pay, which is not the same as what Publishers should get. Cryo.