Class 10 Science Chapter 1 Test Paper With Solution
Chapter 1 of Class 10 Science, titled Chemical Reactions and Equations, introduces students to the fundamental concepts of chemical reactions and their representations.
It explains how chemical equations depict reactions with reactants and products, using symbols and formulas. Key concepts include types of reactions like combination, decomposition, displacement, and redox reactions, along with the importance of balancing equations to satisfy the law of conservation of mass.
Class 10 Science Chapter 1
Section A: (1 Mark each)
Q1. Which of the following is a combination reaction?
A) 2H₂ + O₂ → 2H₂O
B) 2Na + Cl₂ → 2NaCl
C) Zn + CuSO₄ → ZnSO₄ + Cu
D) CaCO₃ → CaO + CO₂
Q2. What is the change in the oxidation state of oxygen in H₂O₂ to H₂O?
A) +2 to +1
B) 1 to 2
C) 0 to 1
D) +1 to 1
Q3. What is the product formed when sodium bicarbonate is heated?
A) Na₂CO₃
B) NaOH
C) NaCl
D) Na₂O
Q4. Which of the following is not an example of a redox reaction?
A) 2Na + Cl₂ → 2NaCl
B) H₂ + Cl₂ → 2HCl
C) 2CuSO₄ → 2CuO + SO₂ + O₂
D) H₂O → H₂ + O₂
Q5. Which of the following statements about a chemical equation is incorrect?
A) The number of atoms of each element is the same on both sides of the equation.
B) A chemical equation must be balanced to obey the law of conservation of mass.
C) Coefficients in a chemical equation are written to balance the charges.
D) A chemical equation must show the physical state of the reactants and products.
Section B
Q6. Define a chemical reaction. Give one example.
Q7. Write a balanced chemical equation for the reaction between zinc and hydrochloric acid. Name the products.
Q8. What is meant by a displacement reaction? Give an example.
Q9. Why do chemical reactions need to be balanced? Give an example of a balanced reaction.
Q10. What is meant by the term ‘oxidation’? Give an example of an oxidation reaction.
Section C
Q11. Describe the process of decomposition reaction with an example. Write the balanced chemical equation for the thermal decomposition of calcium carbonate.
Q12. Explain the concept of a double displacement reaction with an example. Write the balanced equation for the reaction between sodium chloride and silver nitrate.
Q13. What is a redox reaction? Explain with an example how oxidation and reduction occur simultaneously in a reaction.
Q14. Explain why the reaction between magnesium and hydrochloric acid is considered a combination reaction. Write the balanced chemical equation.
Q15. Write a balanced chemical equation for the reaction between potassium permanganate and hydrogen peroxide in acidic medium. Explain the changes in oxidation states of manganese and oxygen.
Also Check: Previous Year Question Paper of Chemistry for Class 12
Section D
Q16. (a) What are exothermic and endothermic reactions? Explain with one example of each.
(b) Explain how the process of respiration in living organisms is an exothermic reaction.
Q17. (a) Write a balanced chemical equation for the reaction of calcium oxide with water.
(b) What is the role of calcium oxide in the setting of cement?
Q18. (a) What is meant by corrosion? Write the chemical reaction of rusting of iron.
(b) What are some methods to prevent corrosion?
Section E
Case based Questions (4 Marks each)
Q19. Case Study:
During a laboratory experiment, a student mixed hydrochloric acid (HCl) with zinc metal. The reaction was observed to produce a colorless gas. The gas was tested with a burning splint, and it produced a ‘pop’ sound.
Questions:
a) What is the gas produced in this reaction?
b) Write the balanced chemical equation for the reaction.
c) Is this an example of a redox reaction? Explain.
d) What is the purpose of testing the gas with a burning splint?
Q20. Case Study:
A student heated copper sulfate pentahydrate (CuSO₄·5H₂O) in a beaker. Upon heating, the blue color of the crystals faded, and a white solid was obtained.
Questions:
a) What was the product formed after heating copper sulphate pentahydrate?
b) What type of chemical reaction is this?
c) Why did the blue color fade upon heating?
d) Write the balanced chemical equation for the reaction.
Class 10 Science Chapter 1
Solutions
(Section A)
Q1. A) 2H₂ + O₂ → 2H₂O (Combination reaction)
Q2. B) 1 to 2
Q3. A) Na₂CO₃
Q4. C) 2CuSO₄ → 2CuO + SO₂ + O₂ (This is a thermal decomposition, not a redox reaction)
Q5. C) Coefficients in a chemical equation are written to balance the charges. (Coefficients balance atoms, not charges directly)
(Section B)
Q6. A chemical reaction is a process in which reactants transform into products with the breaking and forming of bonds.
Example: 2H₂ + O₂ → 2H₂O.
Q7. Zn + 2HCl → ZnCl₂ + H₂ (Zinc chloride and hydrogen gas are formed).
Q8. A displacement reaction occurs when one element displaces another from its compound.
Example: Zn + CuSO₄ → ZnSO₄ + Cu.
Q9. Chemical reactions need to be balanced to ensure the law of conservation of mass is obeyed.
Example: 2H₂ + O₂ → 2H₂O is balanced with 2 hydrogen atoms and 2 oxygen atoms on both sides.
Q10. Oxidation is the loss of electrons. Example: In the reaction 2Na → 2Na⁺ + 2e⁻, sodium loses electrons and is oxidized.
(Section C)
Q11. A decomposition reaction is a reaction where one reactant breaks down into two or more products.
Example: CaCO₃ → CaO + CO₂.
Q12. A double displacement reaction involves the exchange of ions between two compounds.
Example: NaCl + AgNO₃ → NaNO₃ + AgCl.
Q13. A redox reaction involves both oxidation and reduction occurring simultaneously.
Example: In 2Na + Cl₂ → 2NaCl, Na is oxidized (loses electrons) and Cl₂ is reduced (gains electrons).
Q14. The reaction of magnesium with hydrochloric acid is a combination reaction because magnesium and hydrochloric acid combine to form magnesium chloride and hydrogen gas.
Mg + 2HCl → MgCl₂ + H₂.
Q15. The reaction between potassium permanganate (KMnO₄) and hydrogen peroxide (H₂O₂) in acidic medium is a redox reaction where manganese is reduced and oxygen is oxidized.
Balanced equation: 2KMnO₄ + 3H₂O₂ + 4H⁺ → 2Mn²⁺ + 3O₂ + 4H₂O.
Section D (5 Marks each)
Q16.
a) Exothermic reactions release heat (e.g., combustion of methane), while endothermic reactions absorb heat (e.g., photosynthesis).
b) Respiration is an exothermic reaction because it releases energy in the form of ATP.
Q17.
a) CaO + H₂O → Ca(OH)₂.
b) Calcium oxide reacts with water to form calcium hydroxide, which is used in cement setting.
Q18.
a) Corrosion is the gradual destruction of metal due to chemical reactions with substances in the environment.
Iron rusting: 4Fe + 3O₂ → 2Fe₂O₃.
b) Methods include galvanization, coating with paint, and using alloys.
Section E : (4 Marks each)
Question 19.
a) The gas is hydrogen (H₂).
b) The balanced chemical equation is: Zn + 2HCl → ZnCl₂ + H₂.
c) Yes, this is a redox reaction because zinc is oxidized and hydrogen is reduced.
d) The pop sound indicates the presence of hydrogen gas.
Question 20.
a) The product is anhydrous copper sulfate (CuSO₄).
b) This is a decomposition reaction.
c) The blue color faded due to the loss of water molecules.
d) CuSO₄·5H₂O → CuSO₄ + 5H₂O.
