In which situation should a colour change not be considered evidence of a chemical reaction?
Answer and explanation
Correct answer: A blue copper sulfate solution becoming lighter blue when water is added
When water is added to a copper sulfate solution, its concentration decreases, so the blue colour may become lighter. This dilution is a physical change and does not necessarily form a new substance. In contrast, in option B, the formation of an insoluble precipitate is additional evidence of a new substance being formed.
Frequently asked questions
What is the correct answer to this question?
A blue copper sulfate solution becoming lighter blue when water is added
Why is this the correct answer?
When water is added to a copper sulfate solution, its concentration decreases, so the blue colour may become lighter. This dilution is a physical change and does not necessarily form a new substance. In contrast, in option B, the formation of an insoluble precipitate is additional evidence of a new substance being formed.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Chemical Reactions and Equations.
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