The aqueous solutions of copper sulphate and zinc sulphate appear

Metals and Non-metals

Reactivity Series and Displacement Reactions

Options

(A)blue and green respectively

(B)green and colourless respectively

(C)blue and brown respectively

(D)blue and colourless respectively

Official Answer

The correct option is D.

copper sulphatebluezinc sulphatecolourless

Marking Scheme

11 Mark for selecting the correct option D.

Hint

Think about the colour of the solution in which an iron nail is dipped during the displacement reaction experiment, and the colour of the resulting zinc salt solution.

Quick Oral Answer

Copper sulphate solution is blue, whereas zinc sulphate solution is colourless.

Analysis & Explanation

An aqueous solution of copper sulphate ( $CuSO_4$ ) is characteristically blue in colour due to the presence of hydrated copper ions ( $Cu^{2+}$ ). On the other hand, an aqueous solution of zinc sulphate ( $ZnSO_4$ ) is colourless because zinc ions ( $Zn^{2+}$ ) have a completely filled d-subshell ( $3d^{10}$ ) and do not absorb visible light.

Why Option D is correct: It correctly identifies copper sulphate as blue and zinc sulphate as colourless.
Why Option A is incorrect: Green is the colour of iron(II) sulphate ( $FeSO_4$ ) solution, not zinc sulphate.
Why Option B is incorrect: Copper sulphate is blue, not green.
Why Option C is incorrect: Zinc sulphate is colourless, not brown.

Common Mistakes

1Students often confuse the colourless zinc sulphate solution with the light green iron sulphate ( $FeSO_4$ ) solution.

Interesting Facts

Anhydrous copper sulphate is actually a white powder, but it turns bright blue upon hydration because water molecules coordinate with the copper ions, altering their d-orbital energy levels.

Spotted a mistake or something unclear?

Tell us — we fix reported answers fast.

Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2012?

This question carries 1 mark in the CBSE Class 10 Science 2012 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Metals and Non-metals" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Reactivity Series and Displacement Reactions" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2012 paper?

This is a MCQ question from Section B in the CBSE Class 10 Science 2012 paper.