Question

Colourless concentrated sulfuric acid in a test tube changes to blue on adding a small piece of copper to it .

What is the reason.??????




Please answer fast. ...​

Answer 1

because the copper is basic in nature.

means alkali

Answer 2

Actually,

copper have +ve electrode potential so it displaces hydrogen from it's solution $(H_2SO_4)$

a redox reaction will takes place in which Cu$(SO_4)$ forms..

this reaction can be observed by changement in colours.