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Chemical Reactions and Equations
Science · CBSE Class 10 · English Medium · 21 questions and answers
Sample questions
- Q: What is a chemical reaction?
- A: A process in which one or more substances (reactants) are changed into one or more new substances (products) with different properties.
- Q: What is a chemical equation?
- A: A short-hand representation of a chemical reaction using symbols and formulae of reactants and products.
- Q: Why must a chemical equation be balanced?
- A: To satisfy the law of conservation of mass — the number of atoms of each element must be equal on both sides.
- Q: State the law of conservation of mass.
- A: Mass can neither be created nor destroyed in a chemical reaction; total mass of reactants equals total mass of products.
- Q: What is a combination reaction? Give one example.
- A: A reaction in which two or more substances combine to form a single product. Example: CaO + H₂O → Ca(OH)₂.
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