Q1. [1] § 1.2.5 Oxidation and Reduction
To a small amount of copper oxide in a beaker, when we add dilute hydrochloric acid slowly with stirring, the change in the colour of the solution is due to the formation of :
- (A) Copper(II) oxide, which is black in colour.
- (B) Copper(I) chloride, which is blue in colour.
- (C) Copper(II) chloride, which is blue-green in colour.
- (D) Copper(I) oxide, which is black in colour.
Previously asked in CBSE board exam
2026 31/3/1 Q18
Generated by claude-sonnet-4-6 · 2026-06-14 10:31 · grounding rag
Model Answer
(C) Copper(II) chloride, which is blue-green in colour.
Explanation
Activity 2.7 (Chapter 2) directly states that the solution turns blue-green due to the formation of copper(II) chloride when copper oxide reacts with dilute HCl: CuO + 2HCl → CuCl₂ + H₂O. Remember: metal oxide + acid → salt + water.
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