Which of the following observations is not evidence that a chemical reaction has occurred?
Answer and explanation
Correct answer: Only a change in the position of a substance
A chemical reaction produces one or more new substances, and observations such as gas evolution, a colour change, or precipitate formation may provide evidence of that change. Merely moving a substance from one place to another changes its position, not its composition or identity. It is therefore a physical change and is not evidence by itself that a chemical reaction occurred. Option A is correct.
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What is the correct answer to this question?
Only a change in the position of a substance
Why is this the correct answer?
A chemical reaction produces one or more new substances, and observations such as gas evolution, a colour change, or precipitate formation may provide evidence of that change. Merely moving a substance from one place to another changes its position, not its composition or identity. It is therefore a physical change and is not evidence by itself that a chemical reaction occurred. Option A is correct.
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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