Answer:
Observation 1 is a result of copper atoms losing two electrons.
Explanation:
In the start of the whole process which we can see in picture, what happens is that the copper of the solution is oxidized by the solution of silver nitrate. In this process it loses its two electrons to form Cu2+ which go into the solution of silver nitrate. In the solution ions gain those two electrons lost by copper atoms which replace the copper atoms and which we can see in the form of grey particles on the edge of the strip. Therefore, if we see observation 1 it says that copper strip becomes thinner which evidently is because of the reason that copper is losing electrons and copper level is falling down and silver level is enhancing.
The copper ions in turn react with nitrate ions to form copper nitrate. You can see the whole process in the picture attached.
Hope it helps!
