<h2>Answer:</h2>
Reaction for observation: Sodium Hydroxide + Copper Sulfate
Full reaction:
2NaOH + CuSO4 --> Cu(OH)2 + Na2SO4
<h3>Part 1.</h3>
Observations Before Interaction:
Sodium hydroxide is a turbid solution and copper sulfate is in form of bright blue crystals.
<h3>Part 2:</h3>
Observations After Interaction:
When their solutions are mixed with each other, a pale blue precipitate of basic copper hydroxide & a solution of neutral salt sodium sulphate will be formed.
<h3>Part 3:</h3>
Was Mass Conserved?
Yes, mass was conserved.
The Law of Conservation of Mass states that "mass cannot be created or destroyed, but changed into different forms".
Hence mass was conserved.
<h3>Part 4.</h3><h3>.Proof of a Chemical Reaction</h3>
The proof of the reaction is the appearance of pale blue precipitates of of basic copper hydroxide & a solution of neutral salt sodium sulphate.