Ответ:
1. Water boils if you heat it to 100 C
. (Conditional 0)
2. If you freeze water, it turns into ice. (Conditional 0)
3. What a pity. We would have seen our grandparents if we had arrived on time. (Conditional 3)
5. If I were you, I wouldn't buy that party dress. It’s too expensive. (Conditional 2)
6. Nobody opens the door. If he was at home, he would open the door. (Conditional 2)
7. Someone would catch your handbag if you left it on the table. (Conditional 2)
8. If you were rich, where would you like to live? (Conditional 2)
9. It’s getting late. Her mother will be very angry if she doesn't get home before midnight. (Conditional 1)