Question

Choose the correct answer from the options given below.
A black colour solid which on reaction with dilute sulphuric acid forms a blue coloured solution is:

• A. Carbon
• B. Magnesium(IV) oxide
• C. Lead(II) oxide
• D. Copper(II) oxide

Answer 1

The correct option is D

Copper(II) oxide

Part 1: Explanation for correct answer:-

Option D) Copper(II) oxide

1. When copper(II) which is black is reacted with dilute Sulphuric acid it forms a blue-coloured solution which is Copper sulphate.
2. Reaction is- $$\begin{gathered} \mathrm{CuO}\left(\mathrm{s}\right)\left(\mathrm{black}\right)+{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{CuSO}}_4\left(\mathrm{blue}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \\ \mathrm{Copper}\mathrm{oxide}\mathrm{Sulphuric}\mathrm{Acid}\mathrm{Copper}\mathrm{sulphate}\mathrm{Water} \end{gathered}$$

Part 2: Explanation for incorrect answer:-

Option A) Carbon

1. When carbon is reacted with dilute Sulphuric acid it does not form a blue-coloured solution.

Option B) magnesium(IV) oxide

1. When magnesium(IV) oxide is reacted with dilute Sulphuric acid it does not form a blue-coloured solution.

Option C) lead(II) oxide

1. When lead(II) oxide is reacted with dilute Sulphuric acid it does not form a blue-coloured solution.

Final answer:- A black colour solid which on reaction with dilute Sulphuric acid forms a blue coloured solution is: Option (d) copper(II) oxide