CBSE Class 10 Science Sample Paper 2020 was designed based on the revised syllabus and exam pattern implemented during the pandemic. This paper includes a well-balanced mix of 1-mark objective questions, 2-mark concept-based questions, 3-mark application-based questions, and 5-mark long answer questions.

CBSE Class 10 Science Sample Paper 2020–21

It covers important topics from Physics, Chemistry, Biology, and Environmental Science in line with NCERT guidelines. Practicing this paper helps students understand the latest question formats, improve time management, and gain confidence before the board exam. On this page, you’ll find all 36 questions of the sample paper fully solved in plain text format with bold questions and clear explanations—perfect for quick revision and last-minute preparation.

SECTION A (1 mark each) | CBSE Class 10 Science Sample Paper 2020–21

Q1. Which of the following reactions is an example of a combination reaction?
a) CaO + H₂O → Ca(OH)₂
b) NaCl + AgNO₃ → AgCl + NaNO₃
c) Zn + H₂SO₄ → ZnSO₄ + H₂
d) BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl
Answer: a) CaO + H₂O → Ca(OH)₂
This is a combination reaction where two reactants form a single product.

Q2. What happens when hydrogen gas is passed over heated copper oxide?
Answer: Hydrogen reduces black copper oxide to brown copper metal.
CuO + H₂ → Cu + H₂O

Q3. A solution turns red litmus blue. Its pH is likely to be:
a) 1
b) 4
c) 7
d) 10
Answer: d) 10
The solution is basic, so pH > 7.

Q4. What type of chemical reaction is involved in photosynthesis?
Answer: Endothermic reaction
Light energy is absorbed to convert CO₂ and water into glucose.

Q5. Name the organ which regulates the amount of water in urine.
Answer: Hypothalamus and kidneys regulate water in urine. Antidiuretic hormone (ADH) plays a major role.

Q6. Which structure in nephron acts as the site of filtration?
Answer: Glomerulus
It filters blood under pressure.

Q7. Name the hormone responsible for secondary sexual characteristics in males.
Answer: Testosterone
Secreted by testes during puberty.

Q8. Which method is used by leishmania for reproduction?
Answer: Binary fission along a specific axis
Leishmania is a unicellular protozoan.

Q9. State the function of ozone layer in the atmosphere.
Answer: It protects life on Earth by absorbing harmful ultraviolet (UV) radiation from the sun.

Q10. Which of the following is an eco-friendly activity?
a) Using CFC-based coolers
b) Burning dry leaves
c) Using plastic carry bags
d) Using bicycle for transport
Answer: d) Using bicycle for transport

SECTION B (2 marks each) – CBSE Class 10 Science Sample Paper 2020–21

Q21. Why does the colour of copper sulphate solution change when an iron nail is dipped in it? Write a balanced chemical equation for the reaction.
Answer:
Iron is more reactive than copper and displaces copper from copper sulphate solution.
Reaction: Fe + CuSO₄ → FeSO₄ + Cu
The blue colour of CuSO₄ fades as Cu is displaced.

Q22. Write the name and formula of the product formed when sodium hydrogen carbonate reacts with ethanoic acid. What type of reaction is this?
Answer:
Product: Sodium ethanoate (CH₃COONa), Carbon dioxide (CO₂), Water (H₂O)
Reaction: CH₃COOH + NaHCO₃ → CH₃COONa + CO₂ + H₂O
It is an acid-base and decomposition reaction.

Q23. Explain why a convex mirror is used as a rear-view mirror in vehicles.
Answer:
Convex mirrors give a wider field of view and always form erect, diminished images. This helps drivers see more area behind the vehicle.

Q24. Draw the magnetic field lines around a current-carrying straight conductor.
Answer:
(You can describe here if not using an image)
Magnetic field lines are concentric circles centered on the conductor. Direction is given by the Right-Hand Thumb Rule.

Q25. How do guard cells regulate the opening and closing of stomatal pores?
Answer:
Guard cells swell when water enters (become turgid) — stomata open.
They shrink when water exits (flaccid) — stomata close.

Q26. State two causes of depletion of ozone layer. Name one ozone-depleting substance.
Answer:
Causes:

  1. Use of chlorofluorocarbons (CFCs)
  2. Industrial gases and pollutants
    Ozone-depleting substance: CFCs

SECTION C (3 marks each) – CBSE Class 10 Science Sample Paper 2020–21

Q27. Write the steps involved in cleaning of water in a water treatment plant.
Answer:

  1. Sedimentation: Heavy particles settle
  2. Filtration: Water passed through layers to remove impurities
  3. Chlorination: Adding chlorine to kill germs

Q28. Explain how the sex of a child is determined in human beings.
Answer:

  • Males produce X and Y sperms
  • Females produce only X eggs
  • X egg + X sperm = Girl (XX)
  • X egg + Y sperm = Boy (XY)
    Thus, the father determines the sex of the child.

Q29. How does a solenoid behave like a magnet? Draw its magnetic field pattern.
Answer:
Solenoid behaves like a bar magnet — has N and S poles.
Field lines are straight and parallel inside (uniform), circular outside.

Q30. Write any three advantages of using electric energy over other forms of energy.
Answer:

  1. Clean and pollution-free
  2. Easily transmitted over long distances
  3. Convenient to use and control

Q31. Explain the working of an electric bell.
Answer:

  1. When current flows, electromagnet pulls armature.
  2. Hammer hits bell → sound produced
  3. Circuit breaks → magnet demagnetizes
  4. Armature returns → cycle repeats

Q32. What is biodiversity? Why is it important?
Answer:
Biodiversity is the variety of life forms on Earth.
Importance:

  1. Maintains balance in ecosystems
  2. Provides resources (food, medicine, etc.)

Q33. List any three methods of contraception. How do they work?
Answer:

  1. Condom – barrier method
  2. Copper-T – prevents fertilization
  3. Oral pills – hormonal control, prevent ovulation

SECTION D (5 marks each) – CBSE Class 10 Science Sample Paper 2020–21

Q34. a) Write the balanced chemical equation for the reaction between zinc and sodium hydroxide.
b) State two uses of bleaching powder.

Answer:
a) Zn + 2NaOH → Na₂ZnO₂ + H₂↑ (Sodium zincate + hydrogen gas)
This is a displacement reaction.

b) Uses of bleaching powder:

  1. Used for disinfecting drinking water.
  2. Used as a bleaching agent in textile industry.

Q35. a) Draw a neat diagram of the human excretory system and label: kidney, ureter, urinary bladder, urethra.
b) Mention two functions of the human kidney.

Answer:
a) [You can describe for text-only sites:]
Diagram should include:

  • Kidney (bean-shaped, filters blood)
  • Ureter (tube connecting kidney to bladder)
  • Urinary bladder (stores urine)
  • Urethra (releases urine outside)

b) Functions of kidneys:

  1. Removal of nitrogenous waste like urea from blood
  2. Regulation of water and salt balance (homeostasis)

Q36. a) Explain the concept of natural selection using the example of antibiotic resistance in bacteria.
b) What is variation? Why is it important for species survival?

Answer:
a) Natural selection is the process by which traits that improve survival become common.
Example: Some bacteria mutate and become resistant to antibiotics. These survive and reproduce, passing resistance to offspring.

b) Variation: Differences in traits among individuals of a species.
Importance: It helps species adapt to changing environments and survive long-term.

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For the official Class 10 Mathematics Solutions, you can visit:

  1. NCERT Textbooks (for Class 10):
ncert resources

The CBSE Class 10 Science Sample Paper 2020–21 plays a vital role in helping students practice and revise key concepts from Physics, Chemistry, and Biology. With a variety of question types—from one-mark MCQs to five-mark long answers—this paper helps students prepare strategically for the board exam. By working through each solved question, learners can assess their understanding and gain clarity on how to present answers as expected by CBSE.

Solving the CBSE Class 10 Science Sample Paper 2020–21 not only boosts confidence but also improves time management during the actual exam. Since the paper follows the updated format introduced during the pandemic period, it is an ideal resource for understanding the structure of board papers in a new pattern.

Every question in the CBSE Class 10 Science Sample Paper 2020–21 is aligned with NCERT concepts and the official syllabus, making it a reliable tool for revision. Whether it’s numerical problems in electricity, explanation-based questions in biology, or chemical reactions in chemistry, this paper covers all essential areas of the Class 10 Science curriculum.

In summary, the CBSE Class 10 Science Sample Paper 2020–21 offers complete exam readiness. Students are advised to solve it thoroughly, compare with detailed solutions, and learn the correct way to attempt answers for maximum marks. Regular practice of such sample papers ensures better performance and reduces exam-day stress.