When an iron nail is placed in copper sulphate solution, what is observed?

Correct option is A

The correct answer is (a) Iron dissolves and copper deposits on the nail.

Explanation:

• This process is a classic example of a single displacement reaction, primarily driven by the metal reactivity series.
• Iron (Fe) is placed higher than Copper (Cu) in the reactivity series, making it more chemically reactive.
• When the iron nail is placed in the blue Copper Sulphate (CuSO_4) solution, iron successfully displaces copper from the solution.
• The chemical reaction is: Fe + CuSO_4 \ FeSO_4 + Cu.
• Consequently, the iron gradually dissolves to form Ferrous Sulphate, and a reddish-brown layer of displaced copper coats the iron nail.

Information Booster:

• A clear visual indicator of this reaction is a distinct color change in the liquid.
• The original vibrant blue colour of the Copper Sulphate solution slowly fades and turns into a light green color due to the formation of Ferrous Sulphate (FeSO_4).
• This reaction is standardly used to demonstrate relative reactivity of transition metals.

Additional Knowledge:
Copper dissolves and iron deposits on the nail. (Option b)

• This is scientifically impossible because copper is less reactive than iron and therefore cannot displace iron from its solid state.

Hydrogen gas is evolved. (Option c)

• Hydrogen gas is typically evolved when reactive metals react with dilute acids (like HCl or H₂SO₄), not with salt solutions.

No reaction occurs. (Option d)

• A reaction actively takes place because of the difference in reactivity potentials between Iron and Copper.

So the correct answer is (a)