Question

when you put in a drop of a type of milk in copper sulphate, why would it produce precipitate?

Answer 1

the one that would precipitate are the amino acids of the milk that u used because copper sulfate is an hydrating agent therefore when you put milk in it and milk is rich in protein, so the peptide bonds of the proteins will be hydrated and be broken converting the proteins into individual amino acids and these amino acids are the things that would precipitate in your mixture.