Bihar Board 10th Science Model Paper 2027 — Full Paper With Answers

This model paper is based on the BSEB Class 10th Science pattern for 2027. Total marks: 80 Theory + 20 Practical = 100. Solve the theory section in 3 hours.

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Paper Structure

Section	Type	Questions	Marks
Section A	Objective MCQ (attempt all)	40	40
Section B	Short Answer (attempt 10 of 15)	15	20
Section C	Long Answer (attempt 3 of 5)	5	18
Practical	Lab + Project	—	20

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SECTION A — Objective Questions (1 Mark Each)

Q1. Which of the following is a chemical change?

(a) Melting of ice (b) Dissolving sugar in water (c) Burning of paper (d) Cutting of wood

Answer: (c) Burning of paper

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Q2. The pH of a neutral solution is:

(a) 0 (b) 7 (c) 14 (d) 1

Answer: (b) 7

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Q3. Which gas is produced when dilute hydrochloric acid reacts with zinc?

(a) Oxygen (b) Carbon dioxide (c) Hydrogen (d) Nitrogen

Answer: (c) Hydrogen
(Zn + 2HCl → ZnCl₂ + H₂↑)

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Q4. The focal length of a concave mirror is 10 cm. Its radius of curvature is:

(a) 5 cm (b) 10 cm (c) 20 cm (d) 40 cm

Answer: (c) 20 cm
(R = 2f = 2 × 10 = 20 cm)

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Q5. Which organelle is known as the powerhouse of the cell?

(a) Nucleus (b) Ribosome (c) Mitochondria (d) Chloroplast

Answer: (c) Mitochondria

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Q6. The unit of electric resistance is:

(a) Ampere (b) Volt (c) Ohm (d) Watt

Answer: (c) Ohm

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Q7. In which process do plants make their own food?

(a) Respiration (b) Transpiration (c) Photosynthesis (d) Digestion

Answer: (c) Photosynthesis

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Q8. Which of the following metals is the best conductor of electricity?

(a) Iron (b) Copper (c) Lead (d) Zinc

Answer: (b) Copper

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Q9. The image formed by a plane mirror is:

(a) Real and inverted (b) Virtual and inverted (c) Real and erect (d) Virtual and erect

Answer: (d) Virtual and erect

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Q10. Which gas is released during photosynthesis?

(a) Carbon dioxide (b) Hydrogen (c) Oxygen (d) Nitrogen

Answer: (c) Oxygen

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SECTION B — Short Answer Questions (2 Marks Each — Attempt 10 of 15)

Q11. What is Ohm's Law? Write its mathematical expression.

Answer: Ohm's Law states that the current flowing through a conductor is directly proportional to the potential difference across its ends, provided the temperature remains constant.
Mathematical expression: V = IR
Where V = Voltage (Volts), I = Current (Amperes), R = Resistance (Ohms)

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Q12. Differentiate between acids and bases with two examples each.

Answer:

Property	Acids	Bases
Taste	Sour	Bitter
pH	Less than 7	More than 7
Litmus	Turns blue litmus red	Turns red litmus blue
Examples	HCl, H₂SO₄	NaOH, Ca(OH)₂

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Q13. What is the difference between autotrophic and heterotrophic nutrition? Give one example each.

Answer:
Autotrophic: Organisms prepare their own food using sunlight, water and CO₂. Example: Green plants (photosynthesis)
Heterotrophic: Organisms depend on other organisms for food. Example: Animals, fungi

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Q14. State the law of reflection of light.

Answer:

1. The angle of incidence (∠i) is always equal to the angle of reflection (∠r) — ∠i = ∠r
2. The incident ray, the reflected ray, and the normal at the point of incidence all lie in the same plane.

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Q15. What is a balanced chemical equation? Write the balanced equation for burning of methane.

Answer: A balanced chemical equation has equal numbers of atoms of each element on both sides.
Burning of methane: CH₄ + 2O₂ → CO₂ + 2H₂O

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Q16. Define electric power and write its SI unit.

Answer: Electric power is the rate at which electrical energy is consumed or converted.
P = VI = I²R = V²/R
SI unit: Watt (W)
1 kWh = 1 unit of electricity consumed

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Q17. What is the function of the nephron in the human kidney?

Answer: The nephron is the basic structural and functional unit of the kidney. It filters blood by three processes:

1. Filtration — Blood is filtered at the glomerulus
2. Reabsorption — Useful substances (glucose, water, salts) are reabsorbed
3. Secretion — Waste products are secreted into the filtrate, forming urine

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SECTION C — Long Answer Questions (6 Marks Each — Attempt 3 of 5)

Q18. Describe the process of photosynthesis. Write the balanced chemical equation and name the factors affecting it.

Answer:

Photosynthesis is the process by which green plants use sunlight, water and carbon dioxide to produce glucose and oxygen.

Balanced equation:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in presence of sunlight and chlorophyll)

Process:

• Light reactions occur in the thylakoids — light energy splits water (photolysis), releases O₂ and produces ATP and NADPH
• Dark reactions (Calvin Cycle) occur in the stroma — CO₂ is fixed using ATP and NADPH to produce glucose

Factors affecting photosynthesis:

1. Light intensity — more light increases rate up to a saturation point
2. Carbon dioxide concentration — higher CO₂ increases rate
3. Temperature — optimum temperature around 25–35°C
4. Water availability — water is a raw material; its deficiency reduces rate
5. Chlorophyll content — more chlorophyll increases the rate

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Q19. Explain the magnetic effects of electric current. Describe the construction and working of an electric motor.

Answer:

Magnetic Effect of Electric Current: When current flows through a conductor, it produces a magnetic field around it. This was discovered by Oersted in 1820.

Right Hand Thumb Rule: If the right hand thumb points in the direction of current, the curled fingers show the direction of the magnetic field.

Electric Motor Construction:

• Armature coil (ABCD) — rectangular coil in magnetic field
• Permanent magnets — N and S poles
• Commutator — reverses current direction each half rotation
• Carbon brushes — maintain electrical contact
• Battery — source of current

Working:

1. Current enters coil through brush X
2. Force on AB and CD sides (Fleming's Left Hand Rule)
3. Coil rotates — AB goes down, CD goes up
4. After half turn, commutator reverses current
5. Rotation continues — converts electrical energy to mechanical energy

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Q20. What are the main differences between sexual and asexual reproduction? Describe any two methods of asexual reproduction in plants with examples.

Answer:

Feature	Sexual	Asexual
Parents	Two	One
Gametes	Required	Not required
Variation	Present	Absent
Examples	Humans, flowering plants	Amoeba, Hydra

Asexual reproduction in plants:

1. Budding (in Hydra and Yeast)
A small bud develops on the parent organism, grows into a new individual, and eventually detaches. Yeast reproduces by budding — bud grows from parent cell and separates.

2. Vegetative Propagation
New plants grow from vegetative parts:

• Stem: Sugarcane (cuttings), Potato (stem tubers with eyes)
• Root: Dahlia, Sweet potato (root tubers)
• Leaf: Bryophyllum (adventitious buds on leaf margins)

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Practice Questions (Self Test — No Answers Shown)

1. Draw a labelled diagram of the human excretory system.
2. Explain the process of rusting of iron. How can it be prevented?
3. What is refraction of light? State Snell's Law with formula.
4. Describe the nitrogen cycle with a diagram.
5. What is an electromagnet? List three uses of electromagnets.

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Chapter-Wise Weightage for Science

Chapter	Marks
Chemical Reactions and Equations	8
Acids, Bases and Salts	8
Light — Reflection and Refraction	10
Electricity and Magnetic Effects	13
Life Processes	10
Reproduction	8
Environment and Natural Resources	6
Others	17

Tip: Electricity and Light together carry 23 marks in Bihar Board 10th Science. Drawing clear, labelled diagrams of circuits and ray diagrams earns full marks in long answers.