CBSE Class 10 Science Sample Paper 2022-23 Solution

The CBSE Class 10 Science Sample Paper 2022–23 is designed to help students understand the latest exam pattern, question types, and marking scheme introduced by the board. Practicing this sample paper allows students to assess their preparation, improve time management, and boost confidence before the actual board exams.

On this page, you’ll find the complete set of questions along with well-explained answers in plain text format — making revision simple and effective. Whether you’re focusing on Physics, Chemistry, or Biology, this paper gives a balanced mix of conceptual and application-based questions aligned with the CBSE syllabus.

CBSE Class 10 Science Sample Paper 2022–23 With Answers

Max Marks: 80 | Time: 3 Hours
Question–Answer Format | Bold Questions | Explained Answers

🔹 SECTION A – Objective Type Questions (1 mark each)

Q1. The change in colour of moist litmus paper in the given setup is due to:
Answer: (c) presence of H⁺(aq) in the solution
Litmus changes colour in presence of hydrogen ions released in an acidic solution. Moisture helps release H⁺, causing the colour change.

Q2. In the redox reaction:
MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O
Answer: (b) MnO₂ is reduced to MnCl₂ and HCl is oxidized to Cl₂
Here, Mn⁴⁺ becomes Mn²⁺ (reduction), and Cl⁻ becomes Cl₂ (oxidation).

Q3. What is the correct observation of the reaction shown in the setup?
Answer: (c) Magnesium ribbon burns with brilliant white light
Magnesium reacts with oxygen, releasing energy and forming white magnesium oxide.

Q4. Which gas combination is correct?
Answer: (b) CO₂, Cl₂, CO₂, CO
CO₂ is acidic and a respiration product; Cl₂ is used in water treatment; CO₂ is again a product of respiration; CO from incomplete combustion.

Q5. What happens when copper is placed in ferrous sulphate?
Answer: (c) turns colourless and reddish brown substance is deposited
Copper displaces iron forming reddish brown copper and colourless iron sulphate.

Q6. pH of acetic acid vs hydrochloric acid – conclusion?
Answer: (a) pH of acetic acid is more than that of hydrochloric acid
Acetic acid is weak and less ionized than strong HCl, so pH is higher.

Q7. Identify correct option from four organic compounds.
Answer: (c) Addition of hydrogen in presence of catalyst changes A to C
This is hydrogenation — alkyne/alkene becomes alkane with hydrogen and catalyst.

Q8. In leaf T.S., which layer does most photosynthesis?
Answer: (b) II, III (Palisade and mesophyll cells)
These cells are packed with chloroplasts, where photosynthesis happens.

Q9. Which substance absorbs gas from respiration?
Answer: (b) KOH
Potassium hydroxide absorbs CO₂ produced during respiration.

Q10. Tall pea plant (T) × dwarf (t) → F₁ and F₂ generation:
Answer: (d) 100%, 75%
F₁ = 100% tall (Tt); F₂ (Tt × Tt) = 75% tall: 1 TT, 2 Tt, 1 tt.

Q11. Which figures show correct tropic movement?
Answer: (b) A and C
They show plant bending towards/away from stimulus (light or touch).

Q12. Which pollination type gives most variation?
Answer: (c) B, C and D
Cross-pollination between different plants causes maximum genetic variation.

Q13. Resistance of a copper wire increases because:
Answer: (c) increases
With heat, vibrations in atoms increase, opposing flow of electrons.

Q14. Force on copper wire in magnetic field – directions?
Answer: (b) 2
According to Fleming’s Left-Hand Rule, force can act in two directions.

Q15. Resistance decreases when:
Answer: (b) diameter d is increased
Resistance ∝ 1/area. Larger diameter = lower resistance.

Q16. Magnetic field around straight current-carrying wire:
Answer: (d) Concentric circles
Field lines form concentric circles centered on the wire.

Q17.
Assertion: Silver bromide decomposition is used in black and white photography.
Reason: Light provides energy for this exothermic reaction.
Answer: (c) A is true but R is false
Decomposition is photochemical, not exothermic.

Q18.
Assertion: Height in peas is controlled by enzyme efficiency.
Reason: DNA carries protein-making info.
Answer: (a) Both A and R are true and R is the correct explanation of A

Q19.
Assertion: Amphibians tolerate blood mixing.
Reason: They have two-chambered heart.
Answer: (c) A is true but R is false
Amphibians have a three-chambered heart.

Q20.
Assertion: Solenoid aligns North–South when free.
Reason: It behaves like a bar magnet.
Answer: (a) Both A and R are true and R is the correct explanation of A

🔹 SECTION B – Very Short Answer Questions (2 marks each)

Q21. Write the name and formula of one salt with water of crystallization. Mention its use.
Answer:
Salt: Copper(II) sulphate pentahydrate
Formula: CuSO₄·5H₂O
Use: It is used as a fungicide and in electroplating. The blue colour is due to water of crystallization.

Q22. Why are decomposition reactions opposite to combination reactions? Give one example of each.
Answer:
Decomposition: AB → A + B (Breaks down)
Combination: A + B → AB (Joins)
Example (Combination): 2H₂ + O₂ → 2H₂O
Example (Decomposition): 2H₂O → 2H₂ + O₂

Q23. Why is transport of materials necessary in plants or animals?
Answer:
Organisms need food, oxygen, water, and waste removal. Transport helps deliver these substances to/from cells. In plants, xylem and phloem perform this. In animals, blood circulatory system handles it.

Q24. Name the plant hormone made at shoot tip. How does it help a tendril grow around a support?
Answer:
Hormone: Auxin
When a tendril touches a support, auxin builds on the opposite side, causing that side to grow more and curl around the support.

Q25. What are homologous organs? How do they prove evolution?
Answer:
Homologous organs have the same structure but different functions. Example: arm of human, wing of bat.
They show common ancestry and support the theory of evolution.

Q26. A student sees a compass needle reverse when battery terminals are changed. What does this mean?
Answer:
The magnetic field created by current depends on its direction. Reversing battery terminals changes current direction, hence reversing the magnetic field, making the needle deflect oppositely.

🔹 SECTION C – Short Answer Questions (3 marks each)

Q27. Write any two differences between real and virtual images. State one example each.
Answer:

Real Image	Virtual Image
Formed on a screen	Cannot be formed on screen
Always inverted	Always erect

Example of real image: Image formed on a cinema screen by a projector
Example of virtual image: Image formed by a plane mirror

Q28. Draw ray diagrams to show the principal focus of a concave mirror and convex mirror.
Answer:
(Diagram explanation)

Concave mirror: Rays parallel to principal axis converge and meet at the focus (real focus).
Convex mirror: Rays appear to diverge from a point behind the mirror (virtual focus).

Note for text format:
In concave mirror: Real focus in front of mirror
In convex mirror: Virtual focus behind the mirror

Q29. A student studied the reactions of acetic acid with the following:
(i) litmus solution,
(ii) sodium bicarbonate,
(iii) ethanol in presence of acid.
Write equations and observations.
Answer:
(i) Litmus: Blue litmus turns red (acidic nature)
(ii) Sodium bicarbonate reaction:
CH₃COOH + NaHCO₃ → CH₃COONa + CO₂ + H₂O
Observation: Effervescence due to CO₂
(iii) With ethanol (esterification):
CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O
(Sweet smelling ester is formed)

Q30. Define homologous series. Why are they chemically similar? Write first three members of alkane series.
Answer:
A homologous series is a group of organic compounds with the same functional group and similar chemical properties, differing by a –CH₂– group.

They are chemically similar because they have the same functional group.

First three alkanes:
Methane: CH₄
Ethane: C₂H₆
Propane: C₃H₈

Q31. A student added copper sulphate to iron nails. After some time, she observed a brown layer on the nails and colour change.
(i) What type of reaction is this?
(ii) Write balanced chemical equation.
(iii) Why did the change occur?
Answer:
(i) It is a displacement reaction.
(ii) Fe + CuSO₄ → FeSO₄ + Cu
(iii) Iron is more reactive than copper, so it displaces copper from the solution.

Q32. (a) Define 1 Ohm.
(b) A wire of resistance 6 ohm is stretched to double its length. What will be the new resistance?
Answer:
(a) 1 Ohm: Resistance when 1A current flows under 1V potential.
(b) Resistance ∝ (length)²
New resistance = (2L)² × R / L² = 4 × 6 = 24 ohms

Q33. Name two devices using heating effect of current. State two factors affecting heat produced.
Answer:
Devices: Electric heater, electric iron.
Factors:
(i) Resistance of the conductor
(ii) Time for which current flows
(iii) Magnitude of current (I²R)

SECTION D – Long Answer Questions (5 marks each)

Q34. (a) List three chemical properties of acids.
(b) What is observed when:
(i) Blue litmus is added to vinegar?
(ii) Marble chips are dropped into hydrochloric acid?
(iii) Acetic acid is added to sodium bicarbonate?
Answer:
(a) Chemical Properties of Acids:

React with metals → H₂ gas
React with bases → Salt + water (neutralization)
React with carbonates → CO₂ gas

(b)
(i) Blue litmus turns red (acid)
(ii) Effervescence seen due to CO₂ gas
CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O
(iii) CO₂ gas is released
CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂

Q35. A student obtained images using a convex lens. Complete the table for different object positions.
(Use ray diagrams; text format below)

Object Position	Image Position	Nature of Image
At 2F	At 2F	Real, inverted, same size
Beyond 2F	Between F and 2F	Real, inverted, diminished
Between F and 2F	Beyond 2F	Real, inverted, magnified
At focus F	At infinity	Real, inverted, highly magnified
Between lens and focus F	Same side of lens	Virtual, erect, magnified

Q36. (a) What is the role of diaphragm and ribs during inhalation?
(b) How is oxygen and carbon dioxide transported in humans?
(c) How are lungs protected in the chest cavity?
Answer:
(a) Diaphragm contracts and moves down; ribs move outward and upward → chest cavity enlarges → air enters lungs.

(b)