Class 10 Science
Complete Study Guide
Chapter-wise Q&A • Previous Year Papers • 3 Full Model Papers • MCQs • Practical Questions • Exam Strategies
Dear Class 10 Student — Welcome!
Namaskaar! You've taken a really smart step by opening this guide. Whether you're just starting your revision or burning the midnight oil before the SEBA Matriculation exam, this guide is built for you — in a language you understand, with the exact questions that matter most.
Science might sometimes feel overwhelming — all those reactions, diagrams, laws, and definitions. But here's the truth: SEBA Board Science is very pattern-based. The same types of questions repeat year after year. This guide gives you exactly those questions, with clear, simple answers.
Take it one chapter at a time. Don't rush. Use the revision boxes and memory tricks. And remember — understanding beats memorising every single time. You've got this! 💪
Chapter-wise Important Questions & Answers
Chemical Reactions and Equations
Physical & Chemical Changes • Types of Reactions • Balancing EquationsChemical Reaction
A process in which substances interact to form new substances with different properties.
How to Identify
Change in colour, temperature, state; evolution of gas; formation of precipitate.
Remember This
Reactants → written on left; Products → written on right of arrow in a chemical equation.
Lavoisier's Law
Mass of reactants = Mass of products. That's why we must balance equations.
A chemical equation is a symbolic representation of a chemical reaction using formulae of reactants and products. For example: Mg + O₂ → MgO
Rancidity is the oxidation of fats and oils in food that causes a bad smell and taste. It is prevented by adding antioxidants or storing food in airtight containers.
Types of chemical reactions:
- Combination Reaction: Two or more substances combine to form a single product. e.g., 2H₂ + O₂ → 2H₂O
- Decomposition Reaction: A single compound breaks into two or more simpler substances. e.g., 2H₂O → 2H₂ + O₂ (electrolysis)
- Displacement Reaction: A more reactive element displaces a less reactive one. e.g., Zn + CuSO₄ → ZnSO₄ + Cu
- Double Displacement Reaction: Exchange of ions between two compounds. e.g., NaCl + AgNO₃ → AgCl↓ + NaNO₃
- Oxidation-Reduction (Redox) Reaction: Simultaneous oxidation and reduction. e.g., 2Mg + O₂ → 2MgO
| Exothermic Reaction | Endothermic Reaction |
|---|---|
| Heat is released during the reaction | Heat is absorbed during the reaction |
| Energy of products < energy of reactants | Energy of products > energy of reactants |
| e.g., Burning of coal: C + O₂ → CO₂ + heat | e.g., Photosynthesis: CO₂ + H₂O → glucose + O₂ |
Oxidation: The process of addition of oxygen or removal of hydrogen from a substance.
Example: 2Mg + O₂ → 2MgO (Magnesium is oxidised)
Reduction: The process of removal of oxygen or addition of hydrogen to a substance.
Example: CuO + H₂ → Cu + H₂O (CuO is reduced to Cu)
Redox Reaction: A reaction in which oxidation and reduction occur simultaneously is called a redox reaction.
In the reaction: CuO + H₂ → Cu + H₂O
- CuO loses oxygen → CuO is reduced → CuO is the oxidising agent
- H₂ gains oxygen → H₂ is oxidised → H₂ is the reducing agent
This is a redox reaction where both processes occur simultaneously.
Burning of Magnesium: 2Mg + O₂ → 2MgO
Zinc + Copper Sulphate: Zn + CuSO₄ → ZnSO₄ + Cu
Calcium + Water: Ca + 2H₂O → Ca(OH)₂ + H₂↑
- Balanced equation follows Law of Conservation of Mass
- Exothermic = releases heat; Endothermic = absorbs heat
- Decomposition can be thermal, electrolytic, or photolytic
- Corrosion = slow oxidation; Rancidity = oxidation of food
- State symbols: (s) solid, (l) liquid, (g) gas, (aq) aqueous
- ↑ = gas evolved; ↓ = precipitate formed
Acids, Bases and Salts
pH Scale • Indicators • Preparation of Salts • UsesThe pH of a neutral solution is 7. A solution with pH < 7 is acidic, and pH > 7 is basic/alkaline.
Hydrogen gas (H₂) is produced. e.g., Zn + H₂SO₄ → ZnSO₄ + H₂↑
Base: A substance that produces OH⁻ ions in solution. All bases are not soluble in water.
Alkali: A base that is soluble in water is called an alkali. e.g., NaOH, KOH. All alkalis are bases but all bases are not alkalis.
Properties of Bases:
- Bitter in taste and soapy to touch
- Turn red litmus blue
- React with acids to form salt and water (neutralisation)
- pH value greater than 7
- Conduct electricity in aqueous solution
Chemical Name: Calcium sulphate hemihydrate
Formula: CaSO₄·½H₂O
Preparation: When gypsum (CaSO₄·2H₂O) is heated to 373 K (100°C), it loses ¾ of its water of crystallisation to form Plaster of Paris:
2CaSO₄·2H₂O → 2CaSO₄·H₂O + 3H₂OSetting of Plaster of Paris: When water is added, POP sets (hardens) by reabsorbing water and converting back to gypsum:
CaSO₄·½H₂O + 1½H₂O → CaSO₄·2H₂OUses of Plaster of Paris:
- Used in hospitals for setting broken/fractured bones
- Used by sculptors for making statues and models
- Used in making chalk used on blackboards
- Used as a fire-proofing material
- Used for decorating walls and ceilings
When an acid solution is diluted by adding water:
- The concentration of H⁺ ions per unit volume decreases
- The strength of the acid decreases
- The pH of the solution increases (moves toward 7)
This is because the same number of H⁺ ions are now dispersed in a larger volume of solution. Dilution never completely neutralises an acid — it only weakens it.
Important Safety Note: Always add acid to water (not water to acid) during dilution, as adding water to concentrated acid causes violent exothermic reaction and spattering.
| Indicator | Colour in Acid | Colour in Base | Colour in Neutral |
|---|---|---|---|
| Litmus | Red | Blue | Purple |
| Phenolphthalein | Colourless | Pink/Red | Colourless |
| Methyl Orange | Red | Yellow | Orange |
| Turmeric | Yellow | Red-Brown | Yellow |
Metals and Non-metals
Physical & Chemical Properties • Reactivity Series • Extraction of MetalsSilver (Ag) is the best conductor of electricity, but copper (Cu) is used for electrical wiring due to its lower cost.
Graphite (an allotrope of carbon) is the only non-metal that is a good conductor of electricity.
The thermite reaction is a type of displacement reaction in which aluminium (a more reactive metal) displaces iron from iron oxide (Fe₂O₃).
Fe₂O₃ + 2Al → Al₂O₃ + 2Fe + HeatThis reaction produces a large amount of heat (approximately 3000°C). It is used for welding railway tracks (thermite welding). The molten iron formed fills the gap between the tracks.
Metals are extracted depending on their position in the reactivity series:
1. Metals of Low Reactivity (Bottom — Gold, Silver, Platinum, Copper):
- Found in nature in free state (native state)
- Extracted by simple heating (roasting)
- e.g., 2HgS + 3O₂ → 2HgO + 2SO₂; 2HgO → 2Hg + O₂
2. Metals of Medium Reactivity (Middle — Zinc, Iron, Lead, Copper):
- Found as sulphides or carbonates
- Extracted by reduction with carbon (coke) or by calcination and reduction
- e.g., ZnO + C → Zn + CO (Zinc extracted from ZnO)
3. Metals of High Reactivity (Top — Na, K, Ca, Mg, Al):
- Cannot be reduced by carbon or hydrogen
- Extracted by electrolytic reduction
- e.g., Aluminium extracted by electrolysis of molten alumina (Al₂O₃)
Metal + Non-metal
Transfer of electrons between a metal (loses e⁻) and non-metal (gains e⁻). e.g., NaCl
Prevention Methods
Painting, galvanisation, alloying, electroplating, oiling/greasing. Rusting = corrosion of iron.
Carbon and its Compounds
Covalent Bond • Homologous Series • Functional Groups • IsomersThe valency of carbon is 4. Carbon forms covalent bonds because it can neither lose 4 electrons (too much energy required) nor gain 4 electrons (difficult for nucleus to hold). So it shares electrons to complete its octet.
A homologous series is a series of organic compounds that:
- Have the same general formula
- Differ by –CH₂ unit (14 mass units) from one member to the next
- Have similar chemical properties
- Show a gradual change in physical properties
Alkane Series (General formula: CₙH₂ₙ₊₂):
| Name | Formula | No. of Carbons |
|---|---|---|
| Methane | CH₄ | 1 |
| Ethane | C₂H₆ | 2 |
| Propane | C₃H₈ | 3 |
| Butane | C₄H₁₀ | 4 |
Saponification is the process of making soap by heating a fat or oil with a strong alkali (NaOH or KOH).
Fat/Oil + NaOH → Soap + GlycerolCleansing Action of Soap:
Soap molecules have two ends:
- Hydrophilic end (water-loving) — ionic end that dissolves in water
- Hydrophobic end (water-repelling) — non-ionic hydrocarbon tail that dissolves in oil/grease
When soap is added to dirty clothes, the hydrophobic ends attach to dirt/grease particles while the hydrophilic ends remain in water. This forms structures called micelles, which trap the dirt and are washed away with water.
Ethanoic acid (Acetic acid) is the most commonly used carboxylic acid. It is the component that gives vinegar its sour taste.
Formula: CH₃COOH
Properties:
- It is a colourless liquid with a strong pungent smell
- Its melting point is 290 K — in cold countries it freezes and is called glacial acetic acid
- It is a weak acid — does not completely ionise in water
- It reacts with sodium carbonate to produce CO₂ gas
–CHO Aldehyde group → Aldehydes (e.g., Methanal HCHO)
–COOH Carboxyl group → Carboxylic acids (e.g., Acetic acid)
–CO– Ketone group → Ketones (e.g., Propanone CH₃COCH₃)
–X Halogen group → Haloalkanes (e.g., CH₃Cl)
Life Processes
Nutrition • Respiration • Transportation • ExcretionBile is produced by the liver and stored in the gall bladder. It makes the food coming from the stomach alkaline for pancreatic enzymes to work, and it also emulsifies fats (breaks large fat droplets into smaller ones), increasing their surface area for enzyme action.
| Aerobic Respiration | Anaerobic Respiration |
|---|---|
| Occurs in the presence of oxygen | Occurs in the absence of oxygen |
| Glucose → CO₂ + H₂O + Energy (38 ATP) | Glucose → Lactic acid / Ethanol + CO₂ + Energy (2 ATP) |
| Complete breakdown of glucose | Incomplete breakdown of glucose |
| Occurs in mitochondria | Occurs in cytoplasm |
| e.g., In most living organisms | e.g., Yeast, muscle cells during heavy exercise |
Photosynthesis is the process by which green plants make food (glucose) using sunlight, carbon dioxide, and water in the presence of chlorophyll.
6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂Conditions required:
- Sunlight — energy source for the reaction
- Chlorophyll — pigment in chloroplasts that absorbs light
- Carbon dioxide — enters through stomata
- Water — absorbed from soil by roots
Stages of Photosynthesis:
- Light Reactions (in thylakoid): Light is absorbed, water molecules are split (photolysis), ATP and NADPH are formed, O₂ is released
- Dark Reactions/Calvin Cycle (in stroma): CO₂ is fixed to form glucose using ATP and NADPH
Factors affecting rate of photosynthesis:
- Light intensity — higher light = faster rate (up to a limit)
- CO₂ concentration — higher CO₂ = faster rate
- Temperature — optimum temperature required (20–35°C)
- Water availability
Blood is a connective tissue consisting of:
| Component | Function |
|---|---|
| Plasma (55%) | Liquid part; transports dissolved food, CO₂, hormones, waste products |
| RBC (Red Blood Cells) | Contains haemoglobin; carries oxygen from lungs to body cells |
| WBC (White Blood Cells) | Fights infections; provides immunity by producing antibodies |
| Platelets | Helps in blood clotting to prevent excess bleeding at wound site |
Control and Coordination
Nervous System • Hormones • Reflex Action • Plant MovementsA reflex action is an automatic, involuntary, and rapid response to a stimulus that does not involve conscious thinking. It is controlled by the spinal cord. Example: Withdrawing the hand when touching a hot object.
A synapse is the tiny gap (junction) between two neurons or between a neuron and a muscle.
Transmission across synapse:
- When a nerve impulse reaches the end of one neuron (pre-synaptic neuron), it triggers the release of chemical substances called neurotransmitters
- These chemicals diffuse across the synaptic cleft
- They bind to receptor sites on the next neuron (post-synaptic neuron)
- This generates a new nerve impulse in the next neuron
Plant hormones (Phytohormones) are chemical substances produced by plants that regulate plant growth and responses.
| Hormone | Function |
|---|---|
| Auxins | Promotes cell elongation; causes bending of plants toward light (phototropism); promotes root growth |
| Gibberellins | Promotes stem elongation, seed germination, and breaking of dormancy |
| Cytokinins | Promotes cell division; delays ageing of leaves; helps in fruit development |
| Abscisic Acid | Inhibits growth; causes wilting of leaves; promotes dormancy; closes stomata during drought |
| Ethylene | Promotes fruit ripening; helps in breaking dormancy; causes leaf fall (abscission) |
Electricity
Ohm's Law • Resistance • Series & Parallel • Heating EffectResistance: R = ρL/A (ρ=resistivity, L=length, A=area)
Series Circuit: R_total = R₁ + R₂ + R₃
Parallel Circuit: 1/R = 1/R₁ + 1/R₂ + 1/R₃
Power: P = VI = I²R = V²/R
Joule's Law: H = I²Rt (H=heat, t=time in sec)
Electric Energy: E = Pt = VIt
Ohm's Law: At constant temperature, the current (I) flowing through a conductor is directly proportional to the potential difference (V) across its ends.
V ∝ I → V = IR where R = Resistance (constant)V-I Graph: A straight line passing through the origin (since V is directly proportional to I). The slope of the line gives the resistance: slope = V/I = R. A steeper slope means higher resistance.
Conditions for Ohm's Law: Temperature must remain constant. The graph must be a straight line passing through origin.
For parallel combination:
1/R = 1/R₁ + 1/R₂ + 1/R₃ = 1/2 + 1/3 + 1/6 = 3/6 + 2/6 + 1/6 = 6/6 = 1Therefore, R = 1Ω
Note: In parallel combination, equivalent resistance is always less than the smallest individual resistance.
When electric current passes through a conductor, the conductor gets heated. This is called the heating effect of electric current or Joule's heating effect.
Reason: As electrons move through the conductor, they collide with atoms, converting electrical energy into heat energy.
Joule's Law of Heating: H = I²Rt
Devices based on heating effect:
- Electric iron — uses nichrome heating element
- Electric heater / room heater
- Electric bulb — tungsten filament heats up and gives light
- Electric fuse — melts to protect circuits
Magnetic Effects of Electric Current
Magnetic Field • Fleming's Rules • AC/DC • Electromagnetic InductionFleming's Left-Hand Rule: Stretch the thumb, index finger, and middle finger of the left hand mutually perpendicular to each other. If the index finger points in the direction of the magnetic field, and the middle finger in the direction of current, then the thumb points in the direction of force (motion) on the conductor. This rule is used in electric motors.
Electromagnetic Induction: The phenomenon of producing an induced current in a coil due to a changing magnetic field is called electromagnetic induction. This was discovered by Michael Faraday.
Faraday's Laws of Electromagnetic Induction:
- First Law: Whenever the magnetic flux linked with a circuit changes, an electromotive force (EMF) is induced in the circuit. This induced EMF lasts as long as the change in flux continues.
- Second Law: The magnitude of the induced EMF is directly proportional to the rate of change of magnetic flux.
Application: Electric generators (AC and DC) work on this principle.
Light — Reflection and Refraction
Mirror & Lens Formulae • Refractive Index • Prism • Human EyeMagnification (Mirror): m = -v/u = h'/h
Lens Formula: 1/f = 1/v - 1/u
Magnification (Lens): m = v/u
Power of Lens: P = 1/f (in metres), Unit = Dioptre (D)
Snell's Law: n = sin i / sin r
Refractive Index: n = speed of light in vacuum / speed in medium = c/v
Given: u = –20 cm (object on same side as incident light, so negative)
f = –15 cm (concave mirror, focal length negative)
Using Mirror Formula:
1/f = 1/v + 1/u → 1/(-15) = 1/v + 1/(-20) → 1/v = -1/15 + 1/20 = (-4+3)/60 = -1/60Therefore, v = –60 cm
The image is formed 60 cm in front of the mirror (real and inverted).
Magnification: m = –v/u = –(–60)/(–20) = –3 (image is real, inverted, and magnified 3 times)
| Defect | Cause | Correction |
|---|---|---|
| Myopia (Short-sightedness) | Eyeball too long; image forms in front of retina | Concave lens (diverging) |
| Hypermetropia (Long-sightedness) | Eyeball too short; image forms behind retina | Convex lens (converging) |
| Presbyopia | Ageing; loss of elasticity in eye lens | Bifocal lenses |
| Astigmatism | Irregular curvature of cornea | Cylindrical lens |
Heredity and Evolution
Mendel's Laws • DNA • Genetics • Evolution & Natural SelectionGregor Johann Mendel is known as the "Father of Genetics." He proposed two laws:
Law 1 — Law of Segregation: During gamete formation, the two alleles of each character separate (segregate) and each gamete receives only one allele. These alleles recombine randomly during fertilisation.
Law 2 — Law of Independent Assortment: When two pairs of traits are crossed, the alleles of each pair segregate and are distributed to gametes independently of each other (i.e., the inheritance of one trait does not depend on another).
Sex in humans is determined by the sex chromosomes:
- Female: XX (two X chromosomes)
- Male: XY (one X and one Y chromosome)
During reproduction:
- Eggs from mother always carry X chromosome
- Sperms from father carry either X or Y chromosome
Cross:
Mother (XX) × Father (XY)
Eggs: X, X | Sperms: X, Y
Possible combinations: XX (girl), XY (boy), XX (girl), XY (boy)
Ratio: 50% boys : 50% girls
Conclusion: Sex of a child is determined by the father (which sperm fertilises the egg), not the mother. Practices blaming the mother for the child's sex are scientifically wrong.
Evolution is the gradual change in the genetic characteristics of a population over successive generations, resulting in the development of new species from pre-existing species.
Darwin's Theory of Natural Selection:
- Over-production: All organisms produce more offspring than can survive
- Variation: Individuals within a species show variation (differences) in their characteristics
- Struggle for Existence: There is competition for food, space, and mates — only some individuals survive
- Survival of the Fittest: Individuals with favourable variations are better adapted and survive ("Natural Selection")
- Inheritance: Favourable traits are passed to offspring; unfavourable traits disappear over generations
- New Species: Over thousands of generations, accumulated changes lead to new species (Speciation)
Classic Example: Industrial Melanism in peppered moths in England — dark moths survived better after industrialisation (camouflage against soot-darkened trees) while white moths were eaten by predators.
MCQs, Assertion-Reason, Fill in the Blanks & Match the Following
Instructions: Read assertion (A) and reason (R). Choose: (a) Both A and R are true and R is the correct explanation of A. (b) Both A and R are true but R is NOT the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true.
- The process of gaining oxygen or losing hydrogen during a chemical reaction is called Oxidation.
- The pH of blood in the human body is approximately 7.4.
- The formula of washing soda is Na₂CO₃·10H₂O.
- The SI unit of electric resistance is Ohm (Ω).
- The type of image formed by a plane mirror is always Virtual and Erect.
- The hormone responsible for the fight-or-flight response is Adrenaline.
- The functional unit of the kidney is called the Nephron.
- The number of chromosomes in a human body cell is 46 (23 pairs).
- The phenomenon of splitting of white light into its component colours is called Dispersion of light.
- The chemical name of common salt is Sodium chloride (NaCl).
| Column A | Column B | Answer |
|---|---|---|
| 1. Ohm's Law | A. Law of Segregation | 1 → D |
| 2. Mendel | B. Chlorophyll | 2 → A |
| 3. Photosynthesis | C. Electromagnetic induction | 3 → B |
| 4. Faraday | D. V = IR | 4 → C |
| 5. Saponification | E. Soap making | 5 → E |
| Gland | Hormone | Answer |
|---|---|---|
| Pancreas | A. Thyroxine | Pancreas → D |
| Thyroid | B. Testosterone | Thyroid → A |
| Testes | C. Adrenaline | Testes → B |
| Adrenal | D. Insulin | Adrenal → C |
Important Practical-Based Questions
Experiment: To determine the pH of various solutions using pH paper / universal indicator
Materials needed: pH paper, various solutions (lemon juice, baking soda solution, vinegar, tap water, milk), colour chart.
- Dip pH paper in each solution and observe the colour change
- Compare with the colour chart to find pH
Observations:
- Lemon juice → Red (pH ≈ 2–3, acidic)
- Tap water → Green (pH ≈ 7, neutral)
- Baking soda solution → Blue-green (pH ≈ 8–9, basic)
Common Exam Q: "What colour does universal indicator turn in the presence of a strong acid?" → Answer: Red
Experiment: To verify Ohm's Law using a circuit
Circuit Setup: Battery, key, rheostat (variable resistance), ammeter (in series), voltmeter (in parallel across resistor)
- Vary the voltage using the rheostat and record corresponding current values
- Plot V vs I graph — should be a straight line through origin
- Slope = V/I = R (resistance of the conductor)
Precautions: Ammeter should always be in series; voltmeter in parallel. Note readings only after the circuit is stable. Do not leave the circuit ON for long as it may heat up.
Common Exam Q: "Why is the ammeter connected in series?" → So the same current flows through both the ammeter and the component being tested.
Experiment: To show that CO₂ is released during respiration
Setup: Take germinating seeds in a conical flask. Connect the flask through a delivery tube to lime water.
- Germinating seeds respire and release CO₂
- CO₂ passes through lime water
- Lime water turns milky — proving CO₂ is released
Chemical Reaction: Ca(OH)₂ + CO₂ → CaCO₃↓ + H₂O (CaCO₃ is the white precipitate that makes lime water milky)
Common Exam Q: "What does lime water test for?" → Answer: Carbon dioxide (CO₂)
Experiment: To study the refraction of light through a glass slab
- Place a glass slab on white paper and trace its outline
- Draw a normal at the point of incidence
- Fix pins to define the incident ray; trace refracted ray inside and emergent ray outside
- Measure angle of incidence (i), angle of refraction (r), and angle of emergence (e)
Observation: i = e (incident angle = emergent angle), the emergent ray is parallel to the incident ray but laterally displaced.
Conclusion: Snell's Law holds: n = sin i / sin r
3 Full-Length Model Question Papers with Answer Keys
High-Scoring Questions for Upcoming SEBA Exam
Exam Tips, Common Mistakes & Revision Strategies
Start with Formulae
Spend the first 5 minutes of the exam writing all key formulae on the margin. V=IR, P=VI, 1/f=1/v+1/u, etc. This prevents panic later.
Draw Diagrams First
For 5-mark long answer questions involving diagrams, draw the diagram first and then write. It helps structure your answer and impress the examiner.
Label Your Equations
Always balance chemical equations. Write state symbols (↑ ↓ s l g aq). Examiners give marks for these small details.
Show All Working
In numerical problems, write the formula, substitute values, show calculation steps. Even if the final answer is wrong, you get marks for correct method.
Attempt All Questions
There is no negative marking in SEBA Matriculation. Never leave a question blank. Write whatever you know — partial marks are better than zero.
Manage Time Wisely
Allocate 30 min for MCQs+VSQ, 40 min for short answers, 80 min for long answers, 10 min for diagrams, 20 min for revision.
- Days 1–5: Chemical Reactions, Acids-Bases-Salts (all definitions, reactions, pH)
- Days 6–8: Metals and Non-metals (reactivity series, extraction methods)
- Days 9–11: Carbon and its Compounds (homologous series, functional groups, soaps)
- Days 12–14: Life Processes (digestion, respiration, transportation, excretion)
- Days 15–17: Control and Coordination (nervous system, hormones, plant responses)
- Days 18–20: Reproduction (asexual, sexual, human reproduction)
- Days 21–23: Electricity (Ohm's law, circuits, heating effect, numericals)
- Days 24–25: Magnetic Effects (motor, generator, electromagnetic induction)
- Days 26–27: Light (mirror, lens formulae, defects of vision, dispersion)
- Days 28–30: Heredity, Evolution + Model Paper Practice
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