Question 261 markMCQSection B

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.

Answer keywords:copper sulphatebluezinc sulphatecolourless

Marking scheme

  1. 1.1 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.

Common mistakes

  1. 1.Students often confuse the colourless zinc sulphate solution with the light green iron sulphate (FeSO4FeSO_4) solution.

Analysis and explanation

An aqueous solution of copper sulphate (CuSO4CuSO_4) is characteristically blue in colour due to the presence of hydrated copper ions (Cu2+Cu^{2+}). On the other hand, an aqueous solution of zinc sulphate (ZnSO4ZnSO_4) is colourless because zinc ions (Zn2+Zn^{2+}) have a completely filled d-subshell (3d103d^{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 (FeSO4FeSO_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.

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.

Question details

Q26 of 41 questions

Board
CBSE
Class
Class 10
Subject
Science
Year
2012
Section
Section B
Marks
1
Type
MCQ
Chapter
Metals and Non-metals
Topic
Reactivity Series and Displacement Reactions
Bloom's level
Remembering
Syllabus topic
Reactivity series, displacement reactions

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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.