- If you heat ice, it melts. (
will meltis also possible)
- If there is a shortage of any product, prices of that product go up.
- My parents get angry if I come home late.
As you can see, both the main clause and the if-clause are in the Present Simple.
The zero conditional is often used to give instructions:
- Press the button if you want a receipt.
- If you want to leave a message, speak after the tone.