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SEBA Class 10 Science Question Paper Solved 2024 English Medium
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SCIENCE
2024
SCIENCE OLD PAPER
ALL QUESTION ANSWER
| SECTION – A |
Choose the correct answer:
1. Addition of aqueous solution of barium chloride to aqueous solution of sodium sulphate results in insoluble barium sulphate and the solution of sodium chloride. Which of the following is the correct balanced chemical equation with state symbols for the above Reaction?
(i) BaCⅠ (aq) + NaSO4 (aq) ⟶ BaSO4 (s) ↓ + NaCⅠ (aq)
(ii) BaCⅠ2 (s) + Na2SO4 (s) ⟶ BaSO4 (s) + NaCⅠ (s)
(iii) BaCⅠ2 (aq) + Na2SO4 (s) ⟶ BaSO4 (aq) + 2NaCⅠ (aq)
(iv) BaCⅠ2 (aq) + Na2SO4 (aq) ⟶ BaSO4 (s) ↓ + 2NaCⅠ (aq)
Ans: (iv) BaCⅠ2 (aq) + Na2SO4 (aq) ⟶ BaSO4 (s) ↓ + 2NaCⅠ (aq).
2. Which of the following does not involve a chemical reaction?
(i) Digestion of food.
(ii) Respiration.
(iii) Burning of candles.
(iv) Melting of candles.
Ans: (iv) Melting of candles.
3. Which of the following laws is satisfied by a balanced chemical reaction?
(i) Conservation of momentum.
(ii) Conservation of mass.
(iii) Conservation of energy.
(iv) Conservation of density.
Ans: (ii) Conservation of mass.
4. Which one of the following is an olfactory indicator?
(i) Litmus.
(ii) Turmeric.
(iii) Vanilla.
(iv) Phenolphthalein.
Ans: (iii) Vanilla.
5. Metal oxides are:
(i) Acidic.
(ii) Basic.
(iii) Neutral.
(iv) None of the above.
Ans: (ii) Basic.
6. NaHCO3 and Na2CO3, 10H2O are commonly known as _________ and ___________ respectively.
(i) Washing soda, baking soda.
(ii) Baking soda, washing soda.
(iii) Caustic soda, baking soda.
(iv) Baking soda, caustic soda.
Ans: (ii) Baking soda, washing soda.
7. Consider the following statements regarding tooth decay:
(a) Tooth decay starts at a pH lower than 5.5.
(b) Tooth decay is caused by phosphoric acid which lowers pH.
Which among the following options is correct?
(i) (a) is true and (b) is false.
(ii) (a) is false and (b) is true.
(iii) Both (a) and (b) are true.
(iv) Both (a) and (b) are false.
Ans: (i) (a) is true and (b) is false.
8. Which of the following metals is the most malleable?
(i) Sodium.
(ii) Iron.
(iii) Gold.
(iv) Copper.
Ans: (iii) Gold.
9. If metal A displaces metal B from its solution, then:
(i) A is more reactive than B metal.
(ii) B is more reactive than A metal.
(iii) A and B metals are non – reactive.
(iv) A and B metals are equally reactive.
Ans: (i) A is more reactive than B metal.
10. Cinnabar is a sulphide ore of which metal?
(i) Copper.
(ii) Mercury.
(iii) Aluminium.
(iv) Iron.
Ans: (ii) Mercury.
11. What can be the maximum number of sulphur atoms present in a molecule?
(i) 2
(ii) 4
(iii) 8
(iv) 10
Ans: (iii) 8.
12. The name of a compound containing three carbons and aldehyde as functional group is:
(i) Propene.
(ii) Propanol.
(iii) Propane.
(iv) Propanal.
Ans: (iv) Propanal.
13. Which of the following statements is true for an oxidising agent?
(i) It gives hydrogen.
(ii) It gives oxygen.
(iii) It takes oxygen.
(iv) None of the above.
Ans: (ii) It gives oxygen.
14. In the Periodic Table, which of the following properties increase from top to bottom in a group?
(a) Valency.
(b) Metallic.
(c) Effective nuclear change.
(d) Atomic radius.
(i) (a) and (b).
(ii) (b) and (d).
(iii) (c) and (d).
(iv) (a) and (d).
Ans: (ii) (b) and (d).
15. Elements X forms a chloride with the formula XCI2, which is a solid with high melting point. X would most likely be in same group of the Periodic table as:
(i) Na.
(ii) Mg.
(iii) AI.
(iv) Si.
Ans: (ii) Mg.
16. A spherical mirror and a thin spherical less each a focal length of – 15 cm. The mirror and the lens are likely to be:
(i) Both convex.
(ii) Both concave.
(iii) The mirror is concave and the lens is convex.
(iv) The mirror is convex and the lens is concave.
Ans: (ii) Both concave.
17. A boy is unable to see objects when they are placed 17 cm from his eye but can see objects beyond 40 cm from his eye. This defect can be corrected by using:
(i) Convex lens.
(ii) Concave lens.
(iii) Bifocal lens.
(iv) Contact lens.
Ans: (ii) Concave lens.
18. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object?
(i) Between the principal focus and the centre of curvature.
(ii) At the centre of curvature.
(iii) Beyond the centre of curvature.
(iv) Between the pole of the mirror and its principal focus.
Ans: (iv) Between the pole of the mirror and its principal focus.
19. In an experiment, the variation of current with the applied voltage for a conducting material is obtained as shown below:
Which of the following conclusions is/are true about the conductor?
(a) Current increases linearly with the voltage.
(b) Resistance is different for different values of V.
(c) The slope of the graph is the same for every value of V and I.
(i) (a) only.
(ii) (a) and (c).
(iii) (b) only.
(iv) (a) and (b).
Ans: (iii) (b) only.
20. Which among the following diagrams correctly represents the current – carrying wire and the magnetic field associated with it?
(i)
(ii)
(iii)
(iv)
Ans: (iii)
21. Which of the following correctly describes the magnetic field near a long straight wire?
(i) The field consists of straight lines perpendicular to the wire.
(ii) The field consists of straight lines parallel to the wire.
(iii) The field consists of concentric circles centred on the wire.
(iv) The field consists of radial lines originating from the wire.
Ans: (iii) The field consists of concentric circles centred on the wire.
22. The human eye forms the image of an object at its:
(i) Iris.
(ii) Pupil.
(iii) Retina.
(iv) Cornea.
Ans: (iii) Retina.
23. Why is the colour of the clear sky blue?
(i) Due to reflection of light.
(ii) Due to refraction of light.
(iii) Due to scattering of light.
(iv) Due to atmospheric layers.
Ans: (iii) Due to scattering of light.
24. Which of the following is not derived from the sun’s energy?
(i) Wind energy.
(ii) Geothermal energy.
(iii) Nuclear energy.
(iv) Biomass.
Ans: (iii) Nuclear energy.
25. 1 kWh = _________ Joule.
(i) 3.6 × 105
(ii) 3.6 × 106
(iii) 3.6 × 107
(iv) 3.6 × 108
Ans: (ii) 3.6 × 106
26. The SI unit of power of lens is:
(i) Joule.
(ii) Dioptre.
(iii) ohm.
(iv) Ampere.
Ans: (ii) Dioptre.
27. 1 eV = __________.
(i) 1.602 × 10-18J
(ii) 1.602 × 10-19J
(iii) 1.601 × 10-17 J
(iv) 1.601 × 10-16 J
Ans: (ii) 1.602 × 10-19J
28. Ozen, at the higher levels of the atmosphere, prevents:
(i) Infrared radiations.
(ii) Visible light.
(iii) UV radiations.
(iv) Both (i) and (iii).
Ans: (iii) UV radiations.
29. Which of the following is not a renewable source of energy?
(i) Sun.
(ii) Wind.
(iii) Fossil fuel.
(iv) Water.
Ans: (iii) Fossil fuel.
30. The source of the formation of coal and petroleum is:
(i) Coliform.
(ii) Biomass.
(iii) Greenhouse gas.
(iv) Ocean water.
Ans: (ii) Biomass.
31. From the energy flow diagram, it is confirmed that the flow of energy is:
(i) Unidirectional.
(ii) Multidirectional.
(iii) Upward in air.
(iv) Downward in water.
Ans: (i) Unidirectional.
32. An electron enters a magnetic field at right angle to it as shown in the figure above. The direction of force acting on the electron will be:
(i) To the right.
(ii) To the left.
(iii) Out of the page.
(iv) Into the page.
Ans: (iv) Into the page.
33. A current of 0.5 A is drawn by a filament of an electric bulb for 10 minutes. The amount of electric charge that flows through the circuit is:
(i) 330 C.
(ii) 310 C.
(iii) 320 C.
(iv) 300 C.
Ans: (iv) 300 C.
34. Amoeba engulfs food from its surroundings and forms a food vacuole with the help of the _________.
(i) Pseudopodia.
(ii) Cilia.
(iii) Flagella.
(iv) Tentacles.
Ans: (i) Pseudopodia.
35. Xylem tissues of the plants are responsible for:
(i) Transportation of water.
(ii) Transportation of food.
(iii) Transportation of amino acids.
(iv) Transportation of oxygen.
Ans: (i) Transportation of water.
36. To drive the reactions, endothermic processes in the cell use:
(i) ADP.
(ii) ATP.
(iii) AMP.
(iv) CO2.
Ans: (ii) ATP.
37. The gap between two neurons is called_______.
(i) Dendrite.
(ii) Synapse.
(ii) Axon.
(iv) Impulse.
Ans: (ii) Synapse.
38. Which of the following hormones promotes cell division in plants?
(i) Cytokinin.
(ii) Oestrogen.
(iii) Thyroxin.
(iv) Insulin.
Ans: (i) Cytokinin.
39. Some of the voluntary actions like walking in a straight line, riding a bicycle, picking up a pencil, etc., are controlled by part of the hindbrain called:
(i) Cerebellum.
(ii) Cerebrum.
(iii) Pons.
(iv) Medulla.
Ans: (i) Cerebellum.
40. Single – celled animals like amoeba reproduce by the process of ________:
(i) Binary fission.
(ii) Multiple fission.
(iii) Budding.
(iv) Fragmentation.
Ans: (i) Binary fission.
41. The anther contains___________.
(i) Sepals.
(ii) Ovules.
(iii) Carpels.
(iv) Pollen grains.
Ans: (iv) Pollen grains.
42. Which of the following is not a part of the female reproductive system of human beings?
(i) Ovary.
(ii) Uterus.
(iii) Vas deferens.
(iv) Fallopian tube.
Ans: (iii) Vas deferens.
43. Find out the analogous organs from the following:
(i) Wing of a bat and wing of a bird.
(ii) Wing of a bat and forearm of a human.
(iii) Forearm of a frog and forearm of a lizard.
(iv) Wing of a bird and Forearm of a frog.
Ans: (i) Wing of a bat and wing of a bird.
44. Who put forward the theory of ‘natural selection’ to give the ideal of evolution of species in the 19th century?
(i) Charles Darwin.
(ii) Gregor Johann Mendal.
(iii) Stanley L. Miller.
(iv) Harold C. Urey.
Ans: (i) Charles Darwin.
45. In a Mendelian experiment consisting of breeding a tall plant bearing violet flowers with a short pea plant bearing white flowers, the progenies all with violet flowers were obtained . But almost half of them were obtained to be short. This suggests that the genetic makeup of the tall parent can be depicted as:
(i) TTWW.
(ii) ttww.
(iii) TtWW.
(iv) TtWw.
Ans: (iv) TtWw.
| SECTION – B |
46. (a) What do you mean by redox reaction? Find out the oxidation and reduction half-reaction of the following:
Ans: A redox reaction is defined as a reaction in which oxidation and reduction take place simultaneously, involving the transfer of electrons. Oxidation refers to the loss of electrons, while reduction refers to the gain of electrons.”
In a chemical reaction, when one substance is reduced, the other is oxidized. In the reaction, CuO + H2 → Cu + H2O Cu is reduced whereas Hydrogen is oxidized. The reactions in which oxidation and reduction take place simultaneously are called Redox- reactions.
(b) Write the formula of quicklime and slaked lime.
Ans: The chemical formula:
Quicklime: CaO (Calcium Oxide).
Slaked Lime: Ca(OH)₂ (Calcium Hydroxide).
47. Write the chemical equation involved in the dissolution of HCI in water. Name the ions formed in this reaction.
Ans: The chemical equation for the dissolution of HCl in water is:
HCI (aq) + H2O (I) ⟶ H3O+ (aq) + CI– (aq)
Ions formed:
(i) Hydrogen ion (H3O+)
(ii) Chloride ion (Cl⁻)
48. What do you mean by allotrope? Write the names of two allotropes of carbon. How do they differ structurally?
Ans: Carbon is a non-metal that can exist in different forms. Each form is called an allotrope.
The names of two allotropes of carbon:
(i) Graphite.
(ii) Diamond.
Structural Differences:
Diamond: In diamond, each carbon atom is tetrahedrally bonded to four other carbon atoms forming a three- dimensional network. An allotrope of carbon, is the hardest natural substance known and has a very high melting and boiling point.
Graphite: Another allotrope of carbon, is a conductor of electricity. In graphite, each carbon atom is bonded to three other carbon atoms in flat layers of hexagonal rings.
49. What is amalgam? Name the two metals present in bronze. Is bronze an alloy?
Ans: If one of the metals is mercury, then the alloy is known as an amalgam. Bronze is an alloy primarily composed of copper and tin. It’s a widely used alloy due to its durability, malleability, and resistance to corrosion.
The two main metals present in bronze are copper and tin. Yes, bronze is an alloy. An alloy is a mixture of two or more metals or a metal and a nonmetal.
50. What is a thermite reaction? Write the reaction involved in it. Mention one use of it.
Ans: A thermite reaction is a reaction in which a metal oxide is reduced by using aluminium as the reducing agent.This is an exothermic process that releases heat along with its end products. Iron produced in this cycle is in a liquid/molten state.
The most common thermite reaction involves aluminium reacting with iron(III) oxide (rust) to produce iron and aluminium oxide. The reaction is as follows:
Fe2O3(s) + 2AI (s) → 2Fe (l) + AI2O3 (s)
In this reaction:
Fe₂O₃ is iron(III) oxide (rust).
Al is aluminium powder.
51. What is an effective nuclear charge? How does effective nuclear charge change in group and period in the Periodic table?
Ans: The effective nuclear charge is defined as the net positive charge pulling these electrons towards the nucleus.
Effective nuclear charge (Zeff) is the net positive charge experienced by an electron. Zeff increases across a period.Down a group, Zeff decreases due to increased shielding from additional inner electron shells. In a period, nuclear charge increases from left to right as protons are added to the nucleus while electrons are added to the same energy level, which does not significantly increase shielding.
52. A doctor has prescribed a corrective lens of power + 1.5 D. find the focal length of the lens. Is the prescribed lens diverging or converging?
Ans: Here:
Power of lens (P) = 1/Focal length (f)
Given, Power (P) = + 1.5 D
So, Focal length (f) = 1/P = 1/1.5 = 0.67 metres.
53. Explain two ways to induce current in a coil.
Ans: Different ways to induce a current in a coil:
(i) By rotating the coil between the poles of a U-shaped magnet in a magnetic field.
(ii) By bringing a bar magnet close to the coil or taking it away from it.
(a) Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
Ans: Fossil fuels such as coal and petroleum are two energy sources that are exhaustible. Because there are only limited reserves.These resources are non-renewable and the rate of consumption is much faster than the rate at which they can be replaced.
Or
(b) What is the role of decomposers in the ecosystem?
Ans: Decomposers in ecosystems act as environmental cleaners by decaying dead plants and animals. They decompose complex organic compounds in dead organisms, turning them into simpler substances. Decomposers play an important role in releasing inorganic nutrients back in the environment by decomposing the complex compounds of dead and decaying organisms.
55. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25 cm.
Ans: Here:
P = 1/f
The near point of the hypermetropic eye = 1 m
The near point for a normal eye = 25 cm = 0.25 m
Here: 1/f = 1/v – 1/u
= 1/f = 1/0.25 – 1/1
= 1/f = 4-1 = 3
The focal length f is:
f = ⅓ m = 0.333m
P = 1/f = 1/ 0.333
= 3D.
56. A copper wire has diameter 0.5 mm and resistivity of 1.6 × 10-8 Ωm. What will be the length of this wire to make its resistance 10 Ω?
Ans: Here:
R = p × L/A
R = 10 Ω
p = 1.6 × 10-8 Ωm
L = ?
A cross-section area.
A = 𝜋 × r2
= r = 𝜋 (0.25 × 10-3)2
= 𝜋 × 0.0625 × 10-6
= 1.9635 × 10-8 m2
Now,
L = R × A/ p
= 10Ω × 1.9635 × 10-8m2 / 1.6 × 10-8Ω ×m
= 1.9635 × 10-7 / 1.6 × 10-8
= 12.27 m.
57. (a) Explain why the sky appears dark instead of blue to an astronaut.
Ans: To an astronaut, the sky looks dark and black instead of blue because there is no atmosphere containing air in outer space to scatter sunlight.
(b) Explain the Tyndall effect.
Ans: The Tyndall effect is the phenomenon in which the particles in a colloid scatter the beams of light that are directed at them. This effect is named after the 19th-century physicist John Tyndall.
58. Suppose three resistors R1 = 5 Ω, R2 = 10Ω and R3 = 30 Ω are connected to a battery of 12 V in parallel. Calculate (a) the current through each resistor and (b) the total circuit resistance.
Ans: I = V/R
Current through R1 (5Ω)
I1 = 12V/5Ω = 2.4 A
Current through R2 (10Ω)
I2 = 12 V / 10 Ω = 1.2 A
Current through R3 (30Ω)
I3 = 12 V / 30 Ω = 0.4 A
(b) The total circuit resistance:
1/Rtotal = 1/R1 + 1/R2 + 1/R3
1/Rtotal = 1/5 + 1/10 + 1/30
1/Rtotal = 6/30 + 3/30 + 1/30 = 10/30
Rtotal = 30/10
= 3 Ω
Or
An electric heater of resistance 8Ω draws 15 A from the service mains for 2 hours. Calculate the rate at which heat is developed in the heater.
Ans: H = I2 × R × t
Given:
I = 15 A
R = 8 Ω
t = 2 hours = 2 × 3600 seconds = 7200 seconds
H = (15)2 × 8 × 7200
H = 225 × 8 × 7200
H = 1,296,000 Joules.
P = I2 × R
P = (15)2 × 8 = 225 × 8 = 1800 W.
59. Suggest some approaches towards reduction of consumption of various natural resources.
Ans: Non-renewable resources must be reduced, reused, and recycled. More trees must be planted in order to save our forest resources.
Recycle: Making new products requires the use of resources, but recycling helps reuse the materials we already have. Manufacturing fewer new materials reduce waste, which helping decrease groundwater and air pollution.
Recycle: Recycle paper, use recycled paper, and purchase products that can be recycled.
Organize community activities: Organize community activities to promote sustainable use of natural resources.
Support Sustainable Practices: Encourage the use of eco-friendly technologies, renewable energy sources, and efficient waste management systems.
Conserve and protect our natural resources: reduce, recycle, reuse, turn off water and lights, use renewable fuels, clean the water, pick up litter, plant seeds answers will vary.
60. Where are gastric glands located? What role does the secretion of these glands play during digestion?
Ans: Gastric glands are located in the innermost layer of the stomach wall, called the mucosa. These glands are found in the stomach region. It is located in the wall of the stomach.
Secretions from the salivary glands, stomach, intestine, pancreas, and liver facilitate the digestion and absorption processes and protect the gastrointestinal mucosa from the harmful effects of gastric acid and enzymes.
Or
Name the numerous finger – like projections present in the inner lining of the small intestine. What is the significance of the presence of these structures in large numbers in that region? How is the absorbed food taken to each of the body cells for obtaining energy?
Ans: Villi are small, finger-like projections that protrude from the mucosal lining and increase nutrient absorption. Each villus has many microvilli.
After absorption, the nutrients are carried by the blood vessels (mainly capillaries) in the villi. These nutrients travel through the bloodstream to various body cells, where they are used for energy production, growth, and repair.
61. Draw a longitudinal section of a human heart and show with arrow marketing the course of the flow of blood through it.
Ans:
Or
What is translocation? Name the plant tissue that is involved in this process?
Ans: Translocation is the movement of materials in plants from the leaves to other parts of the plant. Nutrients, mainly sugars, are created in the leaves during photosynthesis. The process of translocation takes place in the phloem cells. Thus the cell involved would be companion cells, sieve elements & parenchymatous tissue.Translocation is the movement of water and other products from one part to another part of a plant. Water acts as the medium of transport.
62. Draw a nerve cell with proper labelling. How is an electrical impulse created and in which direction does this impulse travel? What function do these impulses perform?
Ans:
Electrical impulses are converted into chemical impulses in the synaptic cleft. In the dendritic terminals, this nerve impulse is changed from a chemical to an electrical impulse after leaving the synaptic cleft.It starts with the dendrite, which leads to the cell body, leading to the axon, and finally the axon terminal, which connects to the dendrite of the other neuron through a synapse. Hence, the electrical impulse travels from the dendrite, cell body, axon, to the axonal end.
Or
What are plant hormones? Give an example of a plant hormone that promotes growth and the one that inhibits growth?
Ans: Auxins are the plant hormones that promote growth. They promote stem elongation, stimulate branching in roots and inhibit the growth of lateral buds in plants. Abscisic acid is a plant hormone that inhibits growth in plants. It is synthesised in leaves. It promotes senescence i.e. wilting or fall of leaves. Abscisic acid also inhibits seed germination and development. Plant Growth Promoters – They promote cell division, cell enlargement, flowering, fruiting and seed formation. Examples are auxins, gibberellins and cytokinins.
63. Give two points of differences between binary and multiple fission?
Ans: In binary fission, two individuals are formed from a single parent, whereas in multiple fission the parent body divides into many daughter organisms.Binary fission is the division of one parent cell into two identical daughter cells. It takes place in Amoeba Paramecium Euglena and other protozoa.
Or
Why is DNA copying an essential part of the process of reproduction?
Ans: The replication of DNA ensures that each daughter cell formed at the end of cell division, receives equal amount of DNA. Thus, DNA copying or DNA replication is the only way through which a cell makes additional copies of same DNA which can be transmitted to its offspring.
64. What are fossils? How do fossils help in finding out the route of evolution?
Ans: Fossils tell about the ancient organisms’ life and their evolution on earth millions of years ago. Fossils are direct evidence of evolution.Intermediate fossils act as the links between related species. For example- Archeopteryx is the connecting link between birds and reptiles.Fossils are essential evidence for evolution because they show that life on Earth was different in the past than it is now.
Or
How did Mendel recognize the “dominant” as well as the ‘recessive’ characters in his experiments? Discuss with suitable examples.
Ans: The traits that were visible in the F1 generation are referred to as dominant, and traits that disappear in the F1 generation are described as recessive. Mendel found that paired pea traits were either dominant or recessive. Mendel called the repressed trait of ‘dwarfness’ as ‘recessive trait’ and the expressed trait of ‘tallness’ as the ‘dominant trait’ . In this way, Mendel’s experiments with tall dwarf pea plants showed that the traits may be dominant or recessive .
