Important Questions Chemical Equations and Reactions Class 10
1. Balance the following chemical equations:
Fe + O₂ → Fe₂O₃
H₂SO₄ + NaOH → Na₂SO₄ + H₂O
H₂SO₄ + NaOH → Na₂SO₄ + H₂O
2. Identify the type of reaction for the following equations and balance them:
2Na + Cl₂ → 2NaCl
2KClO₃ → 2KCl + 3O₂
2KClO₃ → 2KCl + 3O₂
3. Explain the role of chemical equations in understanding chemical reactions. Provide an example of a chemical reaction that occurs in daily life and write its balanced equation. (2017, 2018, 2019, 2021)
Explanation on the role of chemical equations and example
4. When a piece of zinc is added to hydrochloric acid, a reaction takes place. Write the chemical equation for the reaction and state the observation that indicates the occurrence of the reaction. (2017, 2018, 2019, 2021)
Zn + 2HCl → ZnCl₂ + H₂
Observation: Bubbling or effervescence indicating the release of hydrogen gas.
Observation: Bubbling or effervescence indicating the release of hydrogen gas.
5. Why is it important to balance chemical equations? Illustrate with an example why unbalanced equations are incorrect. (2017, 2018, 2019, 2020)
It ensures the law of conservation of mass is upheld. Example of an unbalanced equation: Fe + O₂ → Fe₂O₃ is incorrect because the number of atoms on each side is not equal.
6. Write the chemical equations for the following reactions:
Mg + O₂ → MgO
Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂
Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂
7. Define decomposition reactions. Provide an example and write its balanced chemical equation. (2016, 2017, 2018, 2020)
A decomposition reaction is a type of chemical reaction where one reactant breaks down into two or more products. Example: 2HgO → 2Hg + O₂
8. What is a combination reaction? Write the balanced chemical equation for the reaction of nitrogen with hydrogen to form ammonia. (2016, 2017, 2018, 2019)
A combination reaction is where two or more substances combine to form a single product. N₂ + 3H₂ → 2NH₃
9. Describe a displacement reaction with an example. Write the balanced chemical equation for the reaction between iron and copper sulfate solution. (2016, 2017, 2018, 2020)
A displacement reaction occurs when a more reactive element displaces a less reactive element from a compound. Example: Fe + CuSO₄ → FeSO₄ + Cu
10. What is a precipitation reaction? Write a balanced chemical equation for the reaction between barium chloride and sodium sulfate. (2016, 2017, 2018, 2020)
A precipitation reaction forms an insoluble product, known as a precipitate. Example: BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl
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