Class 10 Science Model Paper 2026
Max Marks: 80 | Time: 3 Hours
Section A: Biology
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Reason (R): Transport of food in phloem requires energy in the form of ATP.
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Reason (R): Sperm formation requires a temperature lower than the normal body temperature.
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Reason (R): Herbivores eat grass which contains cellulose, and cellulose takes longer to digest.
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The C-shaped rings of cartilage prevent the trachea from collapsing when there is less air in it, ensuring that the air passage remains open for breathing.
A. "DNA copying is an essential part of the process of reproduction." Justify this statement.
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Answer A: Reproduction involves creating new individuals that look similar to parents. The blueprints for body design are stored in the DNA. Therefore, copying DNA is essential to transmit these characteristics to the next generation.
Answer B:
- Amoeba: Fission can take place in any plane.
- Leishmania: Binary fission occurs in a definite orientation (longitudinal) in relation to its whip-like structure (flagellum).
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Crop fields are man-made and managed by humans. Unlike natural ecosystems (like forests or ponds), in crop fields:
- Plants are selected and grown by humans (monoculture).
- Soil is prepared, irrigated, and treated with fertilizers/pesticides by humans.
- Natural balance is modified for maximum yield.
Hence, they are artificial or man-made ecosystems.
(ii) Name the part of the neuron where information is acquired.
(iii) Through which part does the information travel as an electrical impulse?
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(ii) Acquired at: Dendrite tip.
(iii) Travels through: Axon.
(i) What is the colour of flowers in $F_1$ generation?
(ii) If $F_1$ progeny are self-pollinated, what is the percentage of white flowers in $F_2$ generation?
(iii) Write the genotypic ratio of $F_2$ generation.
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(i) $F_1$: All Violet ($Vv$).
(ii) % White in $F_2$: 25% (Since ratio is 3 Violet : 1 White).
(iii) Genotypic Ratio: 1:2:1 ($1 VV : 2 Vv : 1 vv$).
Case Study: Mendel selected the garden pea plant for his experiments on inheritance. He chose plants with contrasting visible characters. For example, he crossed a plant having round and green seeds ($RRyy$) with a plant having wrinkled and yellow seeds ($rrYY$).
Attempt the following:
A. What were the phenotype and genotype of the $F_1$ generation offspring?
B. Name the law of inheritance stated by Mendel based on this dihybrid cross.
Attempt either subpart C or D.
C. If $F_1$ plants are self-pollinated, what will be the phenotypic ratio in the $F_2$ generation?
D. List the new combinations of characters (phenotypes) observed in the $F_2$ generation that were not present in the parents.
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Answer A:
Phenotype: Round and Yellow seeds.
Genotype: $RrYy$.
Answer B: Law of Independent Assortment (Alleles of different traits separate independently of one another during gamete formation).
Answer C: The standard dihybrid ratio is 9:3:3:1.
Answer D (OR):
The new combinations (Recombinants) are:
1. Round and Yellow.
2. Wrinkled and Green.
*(Note: Parents were Round-Green and Wrinkled-Yellow).*
A. (i) Draw a schematic representation of transport and exchange of oxygen and carbon dioxide during transportation of blood in human beings and label: Pulmonary artery, Vena Cava, Pulmonary vein, Aorta.
(ii) Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
(ii) Where is bile produced and where is it stored?
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Answer A:
(ii) Mammals and birds are warm-blooded. They require high energy to maintain constant body temperature. Separation of blood ensures highly efficient supply of oxygen to the body cells.
Answer B:
(i) (a) HCl: Kills germs, creates acidic medium for Pepsin. (b) Villi: Increases surface area for absorption. (c) Pepsin: Digests proteins.
(ii) Produced in Liver, Stored in Gall Bladder.
Section B: Chemistry
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- Washing Soda: $Na_2CO_3 \cdot 10H_2O$
- Gypsum: $CaSO_4 \cdot 2H_2O$
- Baking Soda: $NaHCO_3$ (Anhydrous, no water molecules).
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$C_4H_8$ follows $C_nH_{2n}$ (Alkene). So, it belongs to a different series.
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Reason (R): Carbon atoms form strong covalent bonds with other carbon atoms to form long chains.
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(i) Dilute Sulphuric Acid reacts with Aluminium powder.
(ii) Dilute Hydrochloric Acid reacts with Iron filings.
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(i) $2Al(s) + 3H_2SO_4(aq) \rightarrow Al_2(SO_4)_3(aq) + 3H_2(g)$
(ii) $Fe(s) + 2HCl(aq) \rightarrow FeCl_2(aq) + H_2(g)$
A. (i) What is Homologous Series? List two characteristics.
(ii) Write the formula of the next homologue of Propanal ($C_2H_5CHO$).
(ii) Why is this reaction important industrially?
(iii) Which catalyst is used?
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Answer A:
(i) A series of compounds with the same functional group and similar chemical properties, where successive members differ by a $-CH_2$ unit.
(ii) Next homologue of Propanal (3 carbons) is Butanal ($C_3H_7CHO$).
Answer B:
(i) Hydrogenation Reaction (Addition Reaction).
$R_2C=CR_2 + H_2 \xrightarrow{Ni} R_2CH-CHR_2$
(ii) It is used to make Vanaspati Ghee (solid fat) from liquid vegetable oils.
(iii) Nickel (Ni) or Palladium (Pd).
(ii) Why do acids not show acidic behaviour in the absence of water?
(iii) Why should water be added to acid and not acid to water during dilution?
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(i) Distilled water is a pure covalent compound with no ions. Rain water dissolves gases ($CO_2, SO_2$) from air to form acids, which dissociate into ions.
(ii) Acids release $H^+$ ions only in the presence of water ($HCl + H_2O \rightarrow H_3O^+ + Cl^-$). Without ions, no acidic property is shown.
(iii) Dilution is highly exothermic. If water is added to concentrated acid, the sudden heat may cause the acid to splash out and break the container. Always add acid to water slowly.
Case Study: A student dropped a few pieces of marble chips in dilute hydrochloric acid contained in a test tube. The evolved gas was passed through lime water.
Attempt the following:
A. What change would be observed in lime water?
B. Write the balanced chemical equation for the reaction when gas is passed through lime water.
Attempt either subpart C or D.
C. What happens if the gas is passed for a long time? Write the equation.
D. Name the substance present in marble chips. How is this substance chemically related to eggshells and chalk?
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Answer A: Lime water turns milky (due to formation of white precipitate).
Answer B:
$Ca(OH)_2(aq) + CO_2(g) \rightarrow CaCO_3(s) + H_2O(l)$
(Lime water + Carbon Dioxide $\rightarrow$ Calcium Carbonate + Water).
Answer C: The milkiness disappears because soluble Calcium Hydrogen Carbonate is formed.
$CaCO_3 + H_2O + CO_2 \rightarrow Ca(HCO_3)_2(aq)$.
Answer D (OR):
Substance: Calcium Carbonate ($CaCO_3$).
Relation: Eggshells, Chalk, and Marble are all different physical forms of the same chemical compound, Calcium Carbonate.
A. (i) What is Saponification? Write the reaction involved.
(ii) Differentiate between physical properties of Ethanol and Ethanoic Acid.
(iii) Draw the electron dot structure of Ethene ($C_2H_4$).
(a) Iron with Steam.
(b) Calcium with Water.
(ii) Name an alloy of Aluminium used for making aircraft parts.
(iii) Why is Gold alloyed with Copper or Silver for making ornaments?
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Answer A:
(i) Alkaline hydrolysis of ester to form soap and alcohol. $CH_3COOC_2H_5 + NaOH \rightarrow CH_3COONa + C_2H_5OH$.
(ii) Ethanol is liquid with pleasant smell, neutral. Ethanoic acid freezes in winter (Glacial acetic acid), smells like vinegar, acidic nature.
Answer B:
(i) (a) $3Fe + 4H_2O(g) \rightarrow Fe_3O_4 + 4H_2$.
(b) $Ca + 2H_2O \rightarrow Ca(OH)_2 + H_2$.
(iii) Pure gold (24 carat) is very soft and deforms easily. Alloying makes it hard and suitable for jewelry.
Section C: Physics
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Power $P = 1/f = 1/(-2) = -0.5 D$.
Reason (R): Strength of the magnetic field at a point is directly proportional to the current flowing through the wire.
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Optically Denser: Carbon disulphide (Higher refractive index = 1.63).
Faster Speed: Ethyl alcohol.
Reason: Speed is inversely proportional to refractive index ($v \propto 1/n$). Since alcohol has a lower index (1.36), light travels faster in it.
A. An electric heater of resistance $8 \Omega$ draws 15 A from the service mains for 2 hours. Calculate the rate at which heat is developed in the heater.
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Answer A:
Rate of heat developed = Power ($P$).
$P = I^2 R = (15)^2 \times 8 = 225 \times 8 = 1800 W$.
(Note: Time is not needed to find the 'rate').
Answer B:
1. In series, voltage is divided. Appliances rated for 220V will not work properly.
2. If one appliance is switched off or fails, the circuit breaks, and all other appliances stop working.
(ii) Calculate the resistance of a wire of length 2 m and cross-sectional area $1.5 \times 10^{-6} m^2$ and resistivity $2.8 \times 10^{-8} \Omega m$.
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(i) Reason: Alloys have higher resistivity than pure metals and do not oxidize (burn) readily at high temperatures.
(ii) Calculation:
$R = \rho \frac{L}{A}$
$R = \frac{2.8 \times 10^{-8} \times 2}{1.5 \times 10^{-6}}$
$R = \frac{5.6}{1.5} \times 10^{-2} \approx 3.73 \times 10^{-2} \Omega = 0.037 \Omega$.
(ii) Also, find the power of the lens.
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(i) Position of Object:
Since image size = object size, the object must be at $2F$.
Also, for real image $v = +50 cm$. So, $u = -50 cm$.
Thus, $2f = 50 \Rightarrow f = 25 cm$.
Needle is placed at 50 cm in front of lens.
(ii) Power:
$f = +25 cm = +0.25 m$.
$P = 1/f = 1/0.25 = +4 Diopter$.
(ii) Explain the Right-Hand Thumb Rule.
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(i) Diagram: (Draw concentric circles around the wire at two points where it passes through the plane. Near the center of the loop, lines are nearly straight).
(ii) Rule: Imagine holding the current-carrying conductor in your right hand such that the thumb points in the direction of the current. Then your fingers will wrap around the conductor in the direction of the magnetic field lines.
Case Study: Human Eye
The human eye is like a camera. Its lens system forms an image on a light-sensitive screen called the retina. The eye can adjust the focal length of its lens to focus on objects at different distances. This ability is called Accommodation.
Attempt the following:
A. What is the nature of the image formed on the retina?
B. Which part of the eye helps in changing the focal length of the eye lens?
Attempt either subpart C or D.
C. A person needs a lens of power -4.5 D for correction of her vision. What kind of defect in vision is she suffering from? Calculate the focal length.
D. Why do we have two eyes instead of one? (Give 2 advantages).
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Answer A: Real and Inverted.
Answer B: Ciliary Muscles.
Answer C:
Negative power indicates a Concave lens, so the defect is Myopia (Near-sightedness).
$f = 1/P = 1/(-4.5) = -0.22 m$ or $-22.2 cm$.
Answer D (OR):
1. Wider Field of View: One eye gives ~150°, two eyes give ~180°.
2. Depth Perception: Ability to judge distance (3D vision).
A. (i) What is meant by 'Series combination' of resistors? Derive the expression for equivalent resistance of three resistors $R_1, R_2, R_3$ connected in series.
(ii) Three resistors of $2\Omega, 3\Omega, 6\Omega$ are connected to a 6V battery. How should they be connected to get a total current of 3A?
(ii) State the rule to find the direction of induced current.
(iii) Draw a diagram of an AC Generator (Dynamo) principle setup (coil between magnets).
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Answer A:
(i) Derivation: $V = V_1 + V_2 + V_3$. Since $V=IR$, $IR_{eq} = IR_1 + IR_2 + IR_3 \Rightarrow R_{eq} = R_1 + R_2 + R_3$.
(ii) To get 3A from 6V, $R_{total} = V/I = 6/3 = 2\Omega$.
This is possible if we connect $3\Omega$ and $6\Omega$ in Parallel ($R_p = \frac{3 \times 6}{3+6} = 2\Omega$). Wait! The question asks for total 2Ω. If we connect only 3 and 6 in parallel, we get 2Ω. So, connect 3Ω and 6Ω in parallel, and leave the 2Ω resistor unused? Or maybe the question implies using all?
Correction: If we connect 3 and 6 in parallel, we get 2. If we add the 2 in series, total becomes 4 (Incorrect).
Solution: We need to get 2Ω using 2, 3, 6. If we connect all three in parallel: $\frac{1}{R} = \frac{1}{2} + \frac{1}{3} + \frac{1}{6} = \frac{3+2+1}{6} = \frac{6}{6} = 1\Omega$ (Too low).
Actually, connecting just 3 and 6 in parallel gives 2Ω. If the question requires using all, the setup might be different. Assuming we must use all: Connect 3 and 6 in series (9), parallel with 2? $\rightarrow \frac{18}{11}$.
Standard Board Logic: Just connect $3\Omega$ and $6\Omega$ in parallel. That gives 2Ω equivalent. (Or the question data implies a specific combination). Let's assume the question meant "How to connect them to get 4A?". No, for 3A, the answer is "Connect 3Ω and 6Ω in parallel".
Answer B (OR):
(i) EMI: The production of electricity (induced current) in a coil due to the changing magnetic field linked with it.
(ii) Fleming's Right-Hand Rule.