Which observation provides the best evidence that a chemical reaction has occurred in an experiment?
Answer and explanation
Correct answer: Observing a colour change, gas evolution, a temperature change, or precipitate formation
A colour change, gas evolution, a temperature change, and precipitate formation are common signs that new substances may have formed; therefore, they provide good evidence of a chemical reaction. In contrast, melting or boiling alone is usually a physical change because no new substance is formed.
Frequently asked questions
What is the correct answer to this question?
Observing a colour change, gas evolution, a temperature change, or precipitate formation
Why is this the correct answer?
A colour change, gas evolution, a temperature change, and precipitate formation are common signs that new substances may have formed; therefore, they provide good evidence of a chemical reaction. In contrast, melting or boiling alone is usually a physical change because no new substance is 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.
