Ответ:
1. If you boil water, it turns (turn) to steam. - нулевое
2. She would be upset if she lost (lose) her earrings. - второе
3. If you study hard, you will pass (pass) the exam. - первое
4. If I were rich, I would go (go) on a cruise around the world. - второе
5. You will become a better player if you practice (practise) more. - первое
6. If my team played (play) better, they could win the cup. - второе
7. They will be disappointed if you don't come (not/come). - первое
8. Ice melts if you heat (heat) it. - нулевое