SEBA Class 10 Science Question Paper Solved 2023

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SEBA Class 10 Science Question Paper Solved 2023

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SCIENCE

2023

SCIENCE OLD PAPER

ALL QUESTION ANSWER

SECTION – A

1. Choose the correct answer:

(i) Which of the following is not an example of metalloid?

(a) Si

(b) Ge

(d) Al

Ans: (d) Al

(ii) Which of the following compound is used in soda – acid fire extinguisher?

(a) NaCl

(b) Na₂CO3

(d) NH₄Cl

Ans: (c) NaHCO₃

(iii) Decomposition of vegetable matters into compost is an example of which of the following class of reaction?

(a) Endothermic reaction.

(b) Exothermic reaction.

(d) None of the above.

Ans: (b) Exothermic reaction.

(iv) When electric current is passed through the coil of a solenoid, then the magnetic field –

(a) increases along the direction of current.

(b) decreases along the direction of current.

(d) becomes zero.

Ans: (c) remains the same at all times.

(v) Which of the following is used to measure the potential difference of a circuit?

(a) Ammeter.

(b) Voltmeter.

(d) Multimeter.

Ans: (b) Voltmeter.

(vi) Which of the following is a conventional source of energy?

(a) Wind energy.

(b) Nuclear energy.

(d) Wave energy.

Ans: (b) Nuclear energy.

(vii) Which of the following can depleted Ozone layer?

(a) Chloroflouro carbon.

(b) Nitrogen.

(d) Oxygen.

Ans: (a) Chloroflouro carbon.

(viii) Which of the following constitute a food chain?

(a) Grass, Wheat and Mango.

(b) Grass, Goat and Human.

(d) Grass, Fish and Goat.

Ans: (b) Grass, Goat and Human.

(ix) Which of the following is responsible for change in the curvature of eye lenses?

(a) Retina.

(b) Iris.

(d) Optic nerve.

Ans: (c) Ciliary muscles.

(x) The focal length of a lens is 1 metre. Its power is –

(a) 0.5 D

(b) 1D

(d) 2D

Ans: (b) 1D

2. Choose the correct answer of the following:

(i) Image formed by a concave mirror is-

(a) real and diminished.

(b) real and enlarged.

(d) virtual and diminished.

Ans: (a) real and diminished.

(ii) If the refractive index of glass is 1.5, then speed of light in glass is –

(a) 2 × 108 m/s

(b) 3 × 105m/s

(d) 3 × 108 m/s

Ans: (a) 2 × 108 m/s

(iii) Breakdown of glucose into pyruvate takes place in the –

(a) Cell cytoplasm.

(b) Mitochondria.

(d) Golgi body.

Ans: (a) Cell cytoplasm.

(iv) The energy currency for most of the cellular processes is –

(a) ADP

(b) AMP

(d) CO2

Ans: (c) ATP

(v) The gap between the two neurons is called a –

(a) dendrite.

(b) synapse.

(d) nerve ending.

Ans: (b) synapse.

(vi) Which of the following is a plant hormone?

(a) Insulin.

(b) Thyroxin.

(d) Cytokinin.

Ans: (d) Cytokinin.

(vii) The process of giving rise to new individual organisms from the body parts of many fully differentiated organisms is known as –

(a) Regeneration.

(b) Budding.

(d) Fission.

Ans: (a) Regeneration.

(viii) Binary fission occurs in-

(a) Amoeba.

(b) Paramoecium.

(d) All of these.

Ans: (d) All of these.

(ix) An example of homologous organs are –

(a) wings of a bird and a bat.

(b) wings of a butterfly and a bat.

(d) wings of a parrot and a honey bee.

Ans: (c) wings of a pigeon and hands of man.

(x) Which of the following chromosome sets will determine the male sex in human infant?

(a) XX

(b) XY

(d) YO

Ans: (b) XY

3. Fill in the gaps:

(i) The hydrocarbon which is the major component of Compressed Natural Gas (CNG) is _______.

Ans: Methane.

(ii) The product ‘X’ of the following reaction is _______.

3Fe(s) + 4H2O(g) → X + 4H₂(g)

Ans: 3Fe(s) + 4H₂O(g) → 3Fe³ + (aq) + 4H₂(g)

(iii) When iron is mixed with nickel and chromium, we get an alloy named _______.

Ans: Stainless steel.

(iv) The process by which some organisms fulfil their carbon and energy requirements and yields their stored form of energy is _______.

Ans: Photosynthesis.

(v) _______ and _______ are the reproductive parts of a flower which contain the germ – cells.

Ans: Stamens, Carpels.

(vi) A feedback mechanism regulates the action of the _______.

Ans: Hormones.

(vii) The _________mirror is used as rear view in vehicles.

Ans: Convex.

(viii) In electric generator, energy converted from ________ energy to ________ energy.

Ans: Mechanical, electrical.

(ix) The 3rd trophic level of a food chain is __________.

Ans: Carnivores.

(x) When combustion takes place in insufficient air ____________ gas (oxygen) produces.

Ans: Carbon monoxide.

4. Answer in very short:

(i) Among K, Na, Ca and Mg, which one is the least reactive metal?

Ans: Na.

(ii) On heating gypsum at 373 K, it loses water molecule and produces a white powder. What is the chemical formula of the white powder?

Ans: (CaSO₄ H₂O).

(iii) Write the thermite reaction.

Ans: The ignition of Aluminium with Ferric oxide is called the thermite reaction.

(iv) Sodium react violently with cold water and immediately catches fire due to the liberation of a particular gas. Identify the gas:

Ans: hydrogen.

(v) What is the least distance of distinct vision of normal eye?

Ans: 25cm.

(vi) State the S.I. unit of electric charge.

Ans: Coulomb.

(vii) Who first discovered that moving magnet can generate electric current in a coil?

Ans: Michael Faraday.

(viii) What is the approximate percentage of methane in Bio-gas?

Ans: The methane content of biogas typically ranges from 45% to 75% by volume, with most of the remainder being CO₂.

(ix) What will happen if a person consumes iodine deficient food?

Ans: Iodine deficiency is the most common cause of thyroid disease, specifically hypothyroidism (underactive thyroid). Hypothyroidism can cause symptoms including severe tiredness, feeling cold, weight gain and an enlarged thyroid (goitre).

(x) How would you define a ‘gene’?

Ans: A gene is the basic physical and functional unit of heredity. Genes are made up of DNA. Some genes act as instructions to make molecules called proteins. However, many genes do not code for proteins.

5. Determine true or false:

(i) In modern periodic table, elements are arranged in 18 vertical columns and 7 horizontal rows.

Ans: True.

(ii) Precipitation reactions produce insoluble salts.

Ans: True.

(iii) Non-metals can displace hydrogen from dilute acids.

Ans: False.

(iv) Coliform is a group of bacteria, found in human brain.

Ans: False.

(v) Roots, stems and leaves of some plants develop into new plants through vegetative propagation.

Ans: True.

SECTION – B

6. Write one method for the preparation of bleaching powder. Write two uses of it.

Ans: CaOCl₂ is the chemical formula of calcium oxychloride which is commonly known as bleaching powder. It is prepared by the reaction of chlorine gas with calcium hydroxide (slaked lime). The reaction involved is given below.

Ca(OH)₂(aq) + Cl₂(g) → CaOCl₂(aq) + H₂O(l)

Following are uses of bleaching powder:

(i) Used for disinfecting water.

(ii) Used for bleaching of cloth.

7. Fine the Product of the following reactions:

(a) CaCO₃ + H₂O_(l) + CO_2(g)→

Ans: CaCO₃(s) + H₂O_(l) + CO₂(g) → Ca (HCO₃)₂ (aq)

(b) Na₂CO₃ + 10H₂O →

Ans: Na₂CO₃ + 10H₂O → Na₂CO₃ . 10H₂O

8. How metallic character of elements changes across periods and groups of periodic table. Explain.

Ans: Metallic character decreases as you move across a period in the periodic table from left to right. This occurs as atoms more readily accept electrons to fill a valence shell than lose them to remove the unfilled shell. Metallic character increases as you move down an element group in the periodic table.

9. (a) Reaction between ethanoic acid and sodium carbonate produces a salt, CO₂ and water. What is the salt?

Ans: Sodium Acetate.

(b) Find ‘X’

Ans:

10. Draw the ray diagram for the image formation by a convex lens, when object is placed at centre of curvature.

Ans: A real inverted image of the same size as the object is formed on the other side of the lens at the centre of curvature when the object is placed at the centre of curvature in front of a convex lens.

11. Decomposition of 2 g of ferrous sulphate crystals when heated generated 1 g solid oxide and two different gases. Identify the solid oxide and both the gases by writing proper chemical reaction.

Ans: 2FeSO₄(s)heat → Fe₂O₃(s) + SO₂(g) + SO₃(g)

The whole oxide type is ferric oxide. There are two other types of gases –

(i) Sulfur dioxide. and

(ii) Sulfur trioxide.

12. What do you mean by Corrosion and Rancidity ? Explain with Examples.

Ans: Corrosion is the deterioration of metals by the reaction of water and oxygen with the formation of an oxide layer on the metal surface. An example of corrosion is rusting. Rancidity is where the food becomes undesirable. An example of rancidity is the exposure of chips packet to air which changes the odor and taste.

13. Write four properties od magnetic lines of force.

Ans: The four properties of magnetic force lines are as follows:

(i) Magnetic lines of force always start from the north pole and end on the south pole.

(ii) Magnetic lines of force are in a state of tension like a stretched string.

(iii) Magnetic lines of force repel each other.

(iv) Magnetic lines of force never intersect each other.

14. Write two disadvantages of fossil fuels.

Ans: Two disadvantages of fossil fuels are as follows –

(i) Fossil fuels emit carbon dioxide when burnt which is a major greenhouse gas and the primary source of pollution. This has contributed to global warming.

(ii) They are a non-renewable resource, i.e., once used they cannot be replaced.

(iii) Combustion of fossil fuels makes the environment more acidic. This has led to unpredictable and negative changes in the environment.

(iv) Harvesting of fossil fuels also causes fatal diseases among the people. For eg., the coal miners often suffer from Black Lung Disease. The natural gas drillers are constantly exposed to chemicals and silica which is dangerous for their health.

15. State any two methods in reducing the problem of waste disposal.

Ans: We can reduce the problem of waste disposal by these methods:

(i) By minimizing the use of disposable items and promoting the use of recycled articles.

(ii) Separating biodegradable and non-biodegradable waste before dumping them.

16. Why should we conserve forests and wildlife?

Ans: We should conserve forests and wildlife because:

(i) Forests provide a large quantity of raw materials for industries and household. and

(ii) Forests help in maintaining a perfect water cycle.

17. What is meant by power of accommodation of the eye?

Ans: The ability of the eye lens to adjust its focal length, so as to clearly focus rays coming from distant as well a near objects on the retina, is called the power of accommodation of the eye.

18. State two factors does the resistance of a conductor depend.

Ans: Resistance of a conductor depends on:

(i) length of the conductor.

(ii) Area of cross section of the conductor.

19. An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy consumed in 2 hours.

Ans: I = 5 A, V = 220 V

T = 2h = 2 × 3600 S

= 7200 S

∴ Power, P = VI

= 220 × 5

= 1100

∴ Electrical power = p × t

= 1100w × 72005

= 7920000 j

= 7.92 × 10⁶J

20. What is Blood pressure ? What are systolic and diastolic pressures ? What should be the normal systolic as well as diastolic pressure values of a normal person ?

Ans: Blood pressure is the pressure on the walls of blood vessels caused by the constant beating of the heart. The maximum pressure at which the blood leaves the heart through the main artery (Aorta) during ventricular contraction is called systolic pressure. The minimum pressure in the arteries during ventricular relaxation of the heart is called the diastolic pressure.

The normal blood pressure values are: Systolic pressure: 120 mm Hg. Diastolic pressure: 80 mm Hg.

What is lymph ? How does it differ from plasma ? What are their Functions ?

Ans: Lymph is watery fluid that moves through your lymphatic system. It differs from plasma in some ways in that the lymph is almost identical to blood plasma but is colorless and low in protein. Lymph carries digested and absorbed fat from the weapon and returns excess fluid from the extracellular matter to the blood.

The functions of interstitial fluid are as follows:

It is used to transport nutrients to the cells.
It enables intercellular communication between the cells.
It removes the metabolic wastes from the cells.

21. What is a neuromuscular junction ? How does a nerve impulse travels from one part to the others of the body ?

Ans: The neuromuscular junction (NMJ) is a synaptic connection between the terminal end of a motor nerve and a muscle (skeletal/ smooth/ cardiac). The neuromuscular junction—where nerves and muscle fibers meet—is an essential synapse for muscle contraction and movement. Improper function of these junctions can lead to the development of progressive neuromuscular diseases, some of which have no effective treatment (like Lou Gehrig’s disease). Now, NIBIB-funded researchers have found a way to model the human neuromuscular junction by growing these synapses in a lab, which could accelerate novel treatments for neuromuscular diseases.

Draw a neat labelled diagram of a nerve cell and state its function.

Ans:

Its function is to conduct nerve impulses from one part of the body to another.

22. Give the differences between binary fission and multiple fission.

Ans: The differences between binary fission and multiple fission are Given Below:

Binary fission	Multiple fission
(i) 2 daughter cells are formed from the splitting of the parent’s cell or Nucleus.	(i) Many daughter cells are formed from the splitting of the parent’s cell or Nucleus.
(ii) Occurs during favourable conditions.	(ii) Occurs during unfavourable conditions.
(iii) Divides only once.	(iii) Divides repeatedly.
(iv) Both the Nucleus and cytoplasm divide simultaneously.	(iv) First, the nucleus divides and is surrounded by cytoplasm.
(v) Includes definite pattern of division. Example: Amoeba, Bacteria, Euglena, etc.,	(v) Has no definite pattern of division. Example: Plasmodium, Sporozoans, Algae, etc.

State the advantages in plants raised through vegetative propagation.

Ans: Vegetative propagation is practiced for growing some types of plants because:

1. It helps in preservation of characters of the plants through successive generation.

2. Seedless plants can be grown through vegetative reproduction. Through cutting and grafting methods, flowers and fruits can be grown in a shorter time.

3. It is cheaper, easier and more rapid method of plant propagation.

23. What factors could lead to the rise of a new species ?

Ans: Factors that would lead to the rise of a new species are:

(i) Natural Selection.

(ii) Genetic Drift.

(iii) Geographical isolation of a population (lack of gene flow).

If both parents as well as the children are found to possess light eye colour then, according to you the light eye colour trait is of dominant or recessive nature ?

Ans: No. From the given statement, we cannot say with certainty whether light eye colour is dominant or recessive. However, since both the offspring and the parents have light eye colour, the possibility is that light eye colour is a recessive trait.

24. (a) Comment on the electrical conductivity of ionic compounds in solid and molten states.

Ans: In ionic compounds, electricity is conducted by ions. In solid state, ions are held together by strong electrostatic forces and are not free to move about within the solid. Hence, in molten state or in solution form, the ions are free to move and can conduct electricity.

(b) How Electrolytic reduction is used for the extraction of metals?

Ans: During the process of electrolytic reduction, metals get deposited at the cathode, which is the negative electrode. Electrolytic reduction is used to extract highly reactive metals, such as potassium, as these metals cannot be reduced to aqueous solutions. This happens during the extraction and purification of metals.

25. An object of size 7 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focussed image can be obtained ? Find the size and the nature of the image.

Ans: here,

h = 7cm

u = 27cm

f = – 18cm

h’ = ?

v = ?

We know that,

The curtain should be placed 54cm in front of the mirror.

Again,

The image is honest, and conversely, larger than the target. Size of image = – 14 cm.

26. What is the full from of ‘ATP’ ? Why is it called as the ‘energy currency’ for most of the cellular processes ? How do ‘ATP’ molecules produced ? What is an ‘Endothermic processes’ How do ‘ATP’ molecules used to drive these processes ?

Ans: The full form of ATP’ is – Adenosine Triphosphate.

ATP released in cellular respiration. (ATP) is used in the synthesis of molecules. This ATP is used for various functions of the cell. The energy produced by the breakdown of ATP molecules is used for various functions in the cell. In particular, the energy produced from ATP is also used to cause endothermic reactions in cells.

Chemical reactions in which heat is absorbed are called thermophilic reactions.

The cell needs ATP to carry out endothermic reactions. molecules are applied. Water is used to produce ATP. The amount of energy produced when the phosphate molecule is released is 30.5 K. J/Mol. In the same way that batteries provide energy, cells use ATP for various functions such as muscle contraction, protein synthesis, and nerve impulse transport.

What are the methods of excretion used by the plants to get rid of the excretory materials ?

Ans: Plants get rid of the waste product in the following manner:

(i) Gaseous wastes, like CO₂ and O₂, are expelled from the stomata.

(ii) Water vapour from the leaves through transpiration.

(iii) Solid wastes , stored in the plant body through shedding of leaves, peeling of bark, falling of fruits.

(iv) Gums and Resins excreted from the lenticels in the bark.