eVidyarthi
Menu
  • School
    • Close
    • CBSE English Medium
    • CBSE Hindi Medium
    • UP Board
    • Bihar Board
    • Maharashtra Board
    • MP Board
    • Close
  • Sarkari Exam Preparation
    • Close
    • Notes For Competitive Exams
    • MCQs for Competitive Exams
    • All Govt Exams Preparation
    • NCERT Syllabus for Competitive Exam
    • Close
  • Study Abroad
    • Close
    • Study in Australia
    • Study in Canada
    • Study in UK
    • Study in Germany
    • Study in USA
    • Close
Science Class 10 Maharashtra Board | Menu
  • MCQ Science Class 10 Maharashtra Board
  • Book Science Class 10 Maharashtra Board
  • Question Answers Science Class 10 Maharashtra Board
  • Notes Science Class 10 Maharashtra Board
  • Important Questions Science Class 10 Maharashtra Board
  • Science Class 10

Science and Technology Part – I Important Questions Chapter 3 Class 10 Maharashtra Board

Chemical reactions and equations


Short Questions


1. What is the significance of the arrow in a chemical equation?

Answer : It indicates the direction of the reaction from reactants to products.

2. Why is a chemical equation balanced according to the law of conservation of mass?

Answer : The total mass of atoms in reactants must equal that in products to conserve mass.

3. What distinguishes a combination reaction from other reaction types?

Answer : Two or more reactants combine to form a single product.

4. How does a decomposition reaction differ from a combination reaction?

Answer : A single reactant breaks down into two or more products.

5. What characterizes a displacement reaction?

Answer : A more reactive element displaces a less reactive one from its compound.

6. Why is the reaction between AgNO₃ and NaCl classified as a double displacement reaction?

Answer : The ions (Ag⁺ and Na⁺, NO₃⁻ and Cl⁻) exchange partners to form a precipitate.

7. What indicates an exothermic reaction in a chemical equation?

Answer : Heat is released, often written as “+ Heat” on the product side.

8. Why is the decomposition of CaCO₃ an endothermic reaction?

Answer : It requires heat input to break bonds, indicated by Δ above the arrow.

9. How does the size of reactant particles affect the rate of a chemical reaction?

Answer : Smaller particles increase surface area, speeding up the reaction rate.

10. What role does a catalyst play in a chemical reaction?

Answer : It increases the reaction rate without undergoing permanent chemical change.

11. Why is MnO₂ used in the decomposition of KClO₃?

Answer : It acts as a catalyst, accelerating the release of O₂ gas.

12. What defines an oxidation reaction in terms of electron transfer?

Answer : It involves the loss of electrons by a reactant.

13. How is reduction defined in a redox reaction?

Answer : It involves the gain of electrons or loss of oxygen by a reactant.

14. Why is the reaction CuO + H₂ → Cu + H₂O a redox reaction?

Answer : CuO loses oxygen (reduction), and H₂ gains oxygen (oxidation).

15. What is the chemical formula of rust?

Answer : Fe₂O₃·xH₂O (hydrated iron(III) oxide).

16. Why does rusting occur faster in the presence of salt?

Answer : Salt enhances the electrochemical reaction by increasing conductivity.

17. What causes rancidity in oils and fats?

Answer : Air oxidation produces foul-smelling compounds, altering taste and odor.

18. How do antioxidants prevent rancidity in food?

Answer : They inhibit oxidation reactions, slowing the spoilage process.

19. Why is concentrated H₂SO₄ added slowly to water during dilution?

Answer : To control the exothermic reaction and prevent splashing or evaporation.

20. What is nascent oxygen, and why is it reactive?

Answer : It is a highly reactive single oxygen atom ([O]) formed before O₂ molecule formation.


Long Questions


1. Explain the steps to balance the chemical equation N₂(g) + H₂(g) → NH₃(g).

Answer : Start by writing N₂ + H₂ → NH₃, noting 2 N atoms on the left and 1 on the right, so place a 2 before NH₃: N₂ + H₂ → 2NH₃. Balance H by placing a 3 before H₂ (6 H atoms on both sides): N₂ + 3H₂ → 2NH₃. Verify that 2 N and 6 H atoms are equal on both sides, confirming the balanced equation.

2. Why is the reaction between HCl and NaOH classified as exothermic, and how is it represented?

Answer : The reaction HCl + NaOH → NaCl + H₂O releases heat due to the formation of strong bonds in products. This is indicated by “+ Heat” on the product side in the chemical equation. It’s a neutralization reaction, typical of strong acid-base interactions.

3. Analyze the role of Zn in the displacement reaction with CuSO₄ solution.

Answer : Zinc, being more reactive, displaces Cu²⁺ ions from CuSO₄, forming ZnSO₄ and Cu metal. The reaction is Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s), with Zn oxidizing to Zn²⁺. This demonstrates the reactivity series, where Zn ranks higher than Cu.

4. How does the double displacement reaction between BaSO₄ and K₂CrO₄ form a precipitate?

Answer : BaSO₄ (insoluble) reacts with K₂CrO₄, exchanging ions to form BaCrO₄ (yellow precipitate) and K₂SO₄ (soluble). The equation is BaSO₄(aq) + K₂CrO₄(aq) → BaCrO₄↓ + K₂SO₄(aq). The insoluble BaCrO₄ drives the reaction, as precipitates lower solubility.

5. Evaluate the significance of the law of conservation of mass in balancing chemical equations.

Answer : The law ensures that the number of atoms of each element remains constant before and after a reaction. Balancing equations, like 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O, adjusts coefficients to equalize atom counts. This reflects the principle that mass is neither created nor destroyed.

6. Why is the decomposition of sugar an example of a decomposition reaction, and what are its products?

Answer : Heating sugar (C₁₂H₂₂O₁₁) breaks it into carbon (C) and water (H₂O): C₁₂H₂₂O₁₁ → 12C + 11H₂O. This single reactant yields multiple products, defining a decomposition reaction. The process requires heat, indicating an endothermic nature.

7. Discuss how the concentration of reactants affects the rate of reaction with an example.

Answer : Higher concentration increases collision frequency, speeding up reactions, as seen when concentrated HCl reacts faster with CaCO₃ than dilute HCl. In CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O, concentrated HCl produces CO₂ more rapidly. This is due to more frequent effective collisions.

8. Explain the electrochemical mechanism of rust formation on iron surfaces.

Answer : Iron oxidizes at the anode (Fe → Fe²⁺ + 2e⁻), while oxygen reduces at the cathode (O₂ + 4H⁺ + 4e⁻ → 2H₂O). Fe²⁺ ions form Fe³⁺, which react with water to produce rust (Fe₂O₃·xH₂O). This redox process is accelerated by moisture and salts.

9. How does the presence of a catalyst like MnO₂ affect the decomposition of H₂O₂?

Answer : MnO₂ lowers the activation energy, speeding up H₂O₂ decomposition: 2H₂O₂ → 2H₂O + O₂. It remains unchanged chemically, enabling faster O₂ release without altering the reaction’s products. This demonstrates catalysis in enhancing reaction rates.

10. Why is the reaction between vegetable oil and H₂ a reduction reaction, and what conditions are required?

Answer : Vegetable oil gains hydrogen to form vanaspati ghee, a reduction process: Vegetable oil + H₂ → Vanaspati ghee. It requires 60°C and a Ni catalyst to facilitate hydrogen addition. This hydrogenation reduces unsaturation in the oil’s molecular structure.

11. Analyze the redox reaction 2H₂S + SO₂ → 3S + 2H₂O, identifying the oxidant and reductant.

Answer : H₂S loses hydrogen (oxidation), acting as the reductant, while SO₂ gains hydrogen (reduction), acting as the oxidant. The reaction forms sulfur and water, balancing electron transfer. This simultaneous oxidation-reduction defines it as a redox reaction.

12. How do endothermic and exothermic reactions differ in terms of energy exchange, with examples?

Answer : Endothermic reactions absorb heat (e.g., CaCO₃ → CaO + CO₂ requires heat), breaking bonds. Exothermic reactions release heat (e.g., CaO + H₂O → Ca(OH)₂ + heat), forming stable bonds. The energy change determines their classification and practical applications.

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Ads

HSC Maharashtra – Marathi Medium – Maharashtra Board

📘 Maharashtra Board Exam Resources (Marathi Medium)

  • Maharashtra Board Question Banks (Marathi)
  • Maharashtra Board Sample Papers in Marathi Medium
  • Previous Year Question Papers – Marathi Medium
  • Marathi Notes and Practice Mock Tests for SSC/HSC
  • Includes MCQs (Multiple Choice Questions) in Marathi
  • All resources are available in Marathi Medium

📗 Maharashtra Board Textbooks & PDFs (Marathi Medium)

  • 10th Standard Textbook PDF in Marathi
  • Class-wise Textbook PDF (Marathi Medium)
  • Marathi Digest in PDF
  • SSC/HSC Class Books in Marathi PDF
  • Downloadable PDFs - Marathi Education Board

📒 Marathi Study Material for Maharashtra Board

  • Notes in Marathi
  • Chapter-wise Question & Answer (Solutions) in Marathi
  • Important Questions for SSC – Marathi Medium
  • Summary Important Formulas
  • MCQ's, Question Bank, Sample Papers, Previous Year Paper for cxlass 6th to 12th Std for Maharstra Board

क्लास की बुक (पुस्तक), MCQ, नोट्स इन हिंदी

Download एनसीईआरटी सलूशन, सैंपल पेपर, प्रश्न पत्र इन पीडीएफ

CBSE, उत्तर प्रदेश, मध्य प्रदेश, बिहार, राजस्थान & हरियाणा Board हिंदी माध्यम

कक्षा 6 to 8 हिंदी माध्यम
कक्षा 9 & 10 हिंदी माध्यम
कक्षा 11 हिंदी माध्यम

State Board

यूपी बोर्ड 6,7 & 8
बिहार बोर्ड हिंदी माध्यम

CBSE Board

Mathematics Class 6
Science Class 6
Social Science Class 6
हिन्दी Class 6
सामाजिक विज्ञान कक्षा 6
विज्ञान कक्षा 6

Mathematics Class 7
Science Class 7
SST Class 7
सामाजिक विज्ञान कक्षा 7
हिन्दी Class 7

Mathematics Class 8
Science Class 8
Social Science Class 8
हिन्दी Class 8

Mathematics Class 9
Science Class 9
English Class 9

Mathematics Class 10
SST Class 10
English Class 10

Mathematics Class XI
Chemistry Class XI
Accountancy Class 11

Accountancy Class 12
Mathematics Class 12

Learn English
English Through हिन्दी
Job Interview Skills
English Grammar
हिंदी व्याकरण - Vyakaran
Microsoft Word
Microsoft PowerPoint
Adobe PhotoShop
Adobe Illustrator
Learn German
Learn French
IIT JEE

Study Abroad

Study in Australia: Australia is known for its vibrant student life and world-class education in fields like engineering, business, health sciences, and arts. Major student hubs include Sydney, Melbourne, and Brisbane. Top universities: University of Sydney, University of Melbourne, ANU, UNSW.

Study in Canada: Canada offers affordable education, a multicultural environment, and work opportunities for international students. Top universities: University of Toronto, UBC, McGill, University of Alberta.

Study in the UK: The UK boasts prestigious universities and a wide range of courses. Students benefit from rich cultural experiences and a strong alumni network. Top universities: Oxford, Cambridge, Imperial College, LSE.

Study in Germany: Germany offers high-quality education, especially in engineering and technology, with many low-cost or tuition-free programs. Top universities: LMU Munich, TUM, University of Heidelberg.

Study in the USA: The USA has a diverse educational system with many research opportunities and career advancement options. Top universities: Harvard, MIT, Stanford, UC Berkeley

Privacy Policies, Terms and Conditions, Contact Us
eVidyarthi and its licensors. All Rights Reserved.