Zero conditional:
The zero conditional is used to make statements about the real world, and often refers to general truths, such as scientific facts. In these sentences, the time is now or always and the situation is real and possible.
We can make a zero conditional sentence with two present simple verbs [If + present simple, .... present simple].
- If water reaches 100 degrees, it boils. (It is always true, there can't be a different result sometimes).
- If I eat peanuts, I am sick. (This is true only for me, maybe, not for everyone, but it's still true that I'm sick every time I eat peanuts).