Answer:
The solution becomes colorless and a light blue precipitate is formed.
Explanation:
When sodium hydroxide is added to copper(II) nitrate solution, a precipitate of copper(II) hydroxide is formed.
The solution gradually becomes colorless as the light blue precipitate appears.
The reaction is complete (enough sodium hydroxide has been added) when the blue color of the solution completely disappears.
The equation of the reaction is;
Cu(NO3)2(aq) + 2NaOH(aq) → Cu(OH)2(s) + 2NaNO3(aq)