I to know which chemical equation must I write to show that zink nitrate,ammonium nitrate and aluminium nitrate are acids?

You need to show what you can do. Then we can help you get to the correct answers. Maybe you will get the correct answers all by yourself! Try it.
Hint: look in your textbook for the "hydrolysis of salts".
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You could also give a try with the most basic reaction of acids... acids react with a ? To give water and a salt.