What is observed when concentrated hydrochloric acid is added to an aqueous solution of copper(II) sulfate until no further change occurs?
A pale blue precipitate forms that dissolves in excess concentrated hydrochloric acid to form a yellow-green solution.
The solution changes colour from pale blue to green/yellow-green and no precipitate forms.
A colourless gas is evolved and a green precipitate forms.
The solution remains pale blue and a white precipitate forms.