Select the option that correctly indicates which of the following statements are true. When a piece of magnesium metal is placed in copper sulphate solution:

(i) magnesium displaces copper from copper sulphate solution.

(ii) the blue colour of copper sulphate solution fades.

(iii) a red brown deposit of copper metal is formed on the magnesium piece.

Correct option is B

Sol: The correct answer is (b) i, ii and iii

Analysis of statements in the context of magnesium metal added in copper sulfate solution

(i) Magnesium displaces copper from copper sulfate solution.

• ​True. Magnesium is more reactive than copper, and thus, it displaces copper from its salt solution. This is an example of a displacement reaction where magnesium replaces copper in copper sulfate $$(CuSO_4)$$ to form magnesium sulfate $$(MgSO_4)$$ and copper metal.

(ii) The blue colour of copper sulfate solution fades.

• ​True. Copper sulfate solution is blue due to the presence of copper ions $$(Cu^{2+})$$ As magnesium displaces copper, the copper ions are reduced to copper metal, causing the blue color of the solution to fade.

(iii) A red-brown deposit of copper metal is formed on the magnesium piece.

• ​True. As magnesium displaces copper from the solution, copper metal gets deposited on the magnesium piece. Copper appears as a red-brown solid, forming a visible layer on the magnesium.

All three statements are true.​