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The second conditional is contray to fact when talking about present time:
If I were a rich man, I wouldn't work. (facts- I'm not richh and I work)
The third conditional is contrary to past facts-
If I had known, I'd have been more careful. (I didn't know and I wasn't helpful)
The first and the second, when it is referring to future time, aren't contrary to facts because there are no future facts, only possibilities and probabilities. The zero conditional expresses facts, so it isn't contrary to fact, unless the speaker is a liar (You could say 'if you heat water to 50 degress, it boils. This is contrary to fact, but it is simply because the speaker is wrong or lying and has nothing to do with the conditional form being used. HTH ;-)