Why should a colour change alone not be considered conclusive evidence of a chemical reaction?
Answer and explanation
Correct answer: Because a colour change can also result from a physical change, so other observations or reaction conditions must also be considered.
A colour change can be an indication of a chemical reaction, but it is not always conclusive. For example, dissolving a coloured substance in water or mixing coloured substances can change the observed colour without necessarily forming a new substance. Therefore, other observations, such as precipitate formation, gas evolution, temperature change, or the nature of reactants and products, should also be considered. Option D is incorrect because many reactions show a colour change without producing a gas.
Frequently asked questions
What is the correct answer to this question?
Because a colour change can also result from a physical change, so other observations or reaction conditions must also be considered.
Why is this the correct answer?
A colour change can be an indication of a chemical reaction, but it is not always conclusive. For example, dissolving a coloured substance in water or mixing coloured substances can change the observed colour without necessarily forming a new substance. Therefore, other observations, such as precipitate formation, gas evolution, temperature change, or the nature of reactants and products, should also be considered. Option D is incorrect because many reactions show a colour change without producing a gas.
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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