Examples: Water boils if you heat it to 100 degrees Celsius. A red light comes on if you press the main button. In Type Zero sentences, if can be replaced by when. Examples: When you heat ice, it melts. It gets dark when the sun goes down. Type One Conditional Sentences (open condition)
Conditional Sentences Type 2 refers to an action in the present that could happen if the present situation were different. I don't really expect the situation to change because it is very unlikely. Example: If I had a lot of money, I would travel around the world. Conditional Sentence Type 3 .