Note: The below solutions have been prepared in concise language to suit my Govt school children. Plus the answers have been added to respective units wherever necessary.
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| JKBOSE Class 10th 2024-25 Science Solved Paper |
Section A:
(A) Shaving mirror (B) Rear-view mirror (C) Headlight mirror (D) All of these
Ans: (B) Rear-view mirror
2. When a fine beam of sunlight enters a smoke filled room through a small hole, the phenomenon is known as:
(A) Reflection of light. (B) Refraction of light (C) Tyndall effect. (D) None of these
Ans: (C) Tyndall effect
3. The common refractive defects of vision include Myopia, Hypermetropia and Presbyopia. Choose the correct match:
(A) Myopia-Farsightedness, Hypermetropia-Age related farsightedness, Presbyopia-Shortsightedness
(B) Myopia-Shortsightedness, Hypermetropia-Age related forsightedness, Presbyopia-Farsightedness
(C) Myopia-Shortsightedness, Hypermetropia-Farsightedness, Presbyopia-Age related farsightedness
(D) None of this match is correct
Ans: (C) Myopia-Shortsightedness, Hypermetropia-Farsightedness, Presbyopia-Age related farsightedness
4. For flow of charges in a conducting metallic wire, the electrons move only if there is a difference of electric pressure, called the:
(A) Potential difference (B) Resistance (C) Power (D) Both (A) and (B)
Ans: (A) Potential difference
5. Which property of a proton can change while it moves freely in a magnetic field?
(A) Mass and speed (B) Speed and velocity (C) Mass and momentum (D) Velocity and momentum
Ans: (D) Velocity and momentum
6. A rectangular coil of copper wires is rotated in a magnetic field. The direction of the induced current changes once in each:
(A) Two revolutions (B) One revolution (C) Half revolution (D) One-fourth revolution
Ans: (C) Half revolution
7. NaCl + AgNO3→ AgCl + NaNO3 The above reaction is a:
(A) Displacement reaction (B) Double displacement reaction (C) Combination reaction (D) None
Ans: (B) Double displacement reaction
8. Metals can be beaten into thin sheets. This property is called:
(A) Metallic lustre (B) Malleability (C) Ductility (D) Conductivity
Ans: (B) Malleability
9. Which of the following methods is suitable for preventing an iron frying pan from rusting?
(A) Applying grease (B) Applying paint (C) Applying coating of zinc (D) All of these
Ans: (C) Applying coating of zinc
10 X. The leaves of Nettle have stinging hair, which cause painful stings when touched accidently. This is due to presence of:
(A) Methanoic acid (B) Oxalic acid (C) Citric acid (D) Carbonic acid
Ans: (A) Methanoic acid
10 Y. Bee sting contains which acid:
(A) Ethanoic Acid (B) Formic Acid (C) Oxalic Acid (D) Citric Acid
Ans: B. Formic Acid
10 Y. Name the acid present in Tamarind:
(A) Oxalic Acid B. Acetic Acid C. Tartaric Acid D. Methanoic Acid
Ans: C. Tartaric Acid
11. Which of the following types of medicine is used for treating acidity in stomach ?
(A) Antibiotic (B) Antacid (C) Analgesic (D) Antiseptic
Ans: (B) Antacid
12. Autotrophic nutrition involves:
(A) Intake of simple inorganic material from the environment (B) Using external energy source like the sun
(C) Intake of complex material prepared by other organisms (D) Both (A) and (B)
Ans: (D) Both (A) and (B)
13. Which plant hormone inhibits (stops) growth in plants ?
(A) Cytokinin (B) Auxin (C) Abscisic acid (D) Gibberellins
Ans: (C) Abscisic acid
14. An example of homologous organ is:
(A) Our arm and a dog's forearm (B) Our teeth arid and elephant's tusks (C) Potato and runners of grass (D) All of these
Ans: (D) All of these
15. The use of which chemical has endangered the ozone layer ?
(A) Pesticides (B) CFCs (C) Insecticides (D) None of these
Ans: (B) CFCs
Note: From Q. Nos. 16 to 18, two statements (Assertion-A and Reason-R) are given. Select the correct statement/answer to these questions from the codes A, B, C and D as given below:
Codes: (A) When A and R are true and R is the correct explanation of A.
(B) When A and R are true but R is not the correct explanation of A.
(C) When A is true but R is false. (D) When A is false but R is true.
16. Assertion (A): The two characteristic features seen in carbon, that is tetravalency and catenation.
Reason (R) : Carbon atom has four valence electrons in its outermost shell which makes it possible to form large number of compounds.
Ans: (A) A and R are true and R is the correct explanation of A.
17. Assertion (A): Pollen grains from the carpel stick to the stigma of stamen.
Reason (R) : The fertilized egg cells grow inside the ovules and become seeds.
Ans: (D) A is false but R is true.
18. Assertion (A): Decomposers act as cleaning agents of the environment.
Reason (R) : The decomposers recycle waste material in the hydrosphere.
Ans: (C) A is true but R is false.
Section-B
Series X
Ans: Here,
Magnification (m) = 3
Object Distance (U) = -10
i.e, h'/h = -V/U
i.e, 3 = - V/-10
-V = -30
V = 30
So Image is 30 cm from the mirror.
As given, the mirror is concave and image is real, therefore image is in same side of mirror as that of object.
20. State and explain Ohm's law. Define resistance.
Ans: Ohms law was given by Simon Ohm. It shows relation between Potential (V) across the conductor with Current (I) through it.
Ohms law states that Current flowing in conductor is directly proportional to Potential difference across its ends.
i.e , V ∝ I
V = I × R
Where R is the resistance i.e, Opposition to flow of current.
Resistance: Resistance means the opposition to the flow of current. It is denoted by Ω and its SI unit is Ohm.
21. State the factors on which the strength of magnetic field produced by a current carrying solenoid depend.
Ans: A solenoid is a coil with number of turns of insulated copper wire wound in the form of cylinder.
Factors:
The strength of magnetic field depends on the current flowing through the solenoid
The strength of magnetic field depends on the number of turns of the solenoid
22. Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Ans: When iron reacts with copper sulphate, it displaces copper from copper sulphate solution,
CuSO4 + Fe ----------> FeSO4 + Cu
In this displacement reaction, the blue colour of copper sulphate fades away and green colour is formed.
23. Name the following two compounds of carbon: (i) CH3-CH2-Br (ii) CH3-CH2-OH
Ans: (i) CH3-CH2-Br : Bromo-Ethane
(ii) CH3-CH2-OH: Ethanol
24. Explain the meanings of malleable and ductile.
Ans: Malleable: A substance is said to be malleable if it can be beaten into sheets. E.g Metals
Ductile: A substance is said to be ductile if its can be drawn into wires. E.g Metals
25. Write two differences between autotrophic and heterotrophic nutrition.
Ans:
|
Autotrophic Nutrition |
Heterotrophic Nutrition |
|
In this type of Nutrition, organisms prepare their own
food |
In this type of nutrition, Organisms depend on others for
food |
|
It is of two types: Photoautotrophic and Chemoautotrophic |
It is of many types: Holozoic, Saprotrophic, Parasitic |
|
It includes green plants, blue green algae, euglena, some
bacteria |
It includes animals, non-green plants, fungi, some
bacteria |
26. Write down two differences between reflex action and walking.
Ans:
|
Reflex Action |
Walking |
|
It is
Spontaneous |
It is Voluntary |
|
It is controlled
by Spinal Cord |
It is
controlled by Brain |
|
It increases
protection |
It helps in locomotion |
27. Why is DNA copying an essential part of the process of reproduction?
Ans: DNA copying maintains body design and perfection in different generations of a species.
Error in DNA copying can lead to abnormalities in the population.
28. Why are the traits acquired during the lifetime of an individual not inherited?
Ans: The acquired traits are not inherited because they don't alter the DNA in germ cells.
Series Y
Ans: Given; P = - 2.0
We Know P = 1/F
Or F = 1/P
F = 1/-2
F = - 0.5 m or - 50 cm
Negative sign means the lens is Concave.
20. What do you mean by resistors connected in series ?
Ans: When resistors are connected in series, it means they are placed end-to-end along a single path. In series, same current flows through the circuit.
21. Why don't two magnetic lines of force intersect each other
Ans: The two magnetic lines of force do not intersect each other because at the point of intersection the compass needle then must have to point towards two directions, which is not possible.
22. Why should magnesium ribbon be cleaned before burning in air.
Ans: Ans: Magnesium is very reactive and should be cleaned before burning to remove the Magnesium oxide layer from the ribbon which slows down the burning of magnesium ribbon
23. Write down the structural formula of: (i) Propane (ii) Butane
Ans: (i) Propane: CH₃-CH₂-CH₃
(ii) Butane: CH₃-CH₂-CH₂-CH₃
24. Give an example of each of a metal which: (a) is a liquid at room temperature (b) can be easily cut with a knife
Ans: (a) is a liquid at room temperature: Mercury
(b) can be easily cut with a knife: Sodium
25. How is the small intestine designed to absorb digested food?
Ans: Small intestines have folds called villi. They increase the surface area required to absorb food.
26. Why is the use of iodised salt advisable ?
Ans: The use of iodised salt is advisable because iodine is essential for synthesis of thyroxine by thyroid glands.
27. How does binary fission differ from multiple fission ?
Ans:
|
Binary Fission |
Multiple
Fission |
|
Parent Cell
divides into two daughter cells |
Parent cell
divides into many daughter cells |
|
Cytoplasm
divides after every nuclear division |
Cytoplasm doesn’t
divide after every nuclear division |
|
E.g Most
Bacteria |
E.g. Plasmodium |
28. How does the creation of variations in a species promote survival ?
Ans: The variations that confer an advantage to an individual organism will survive in a population.
Such organisms leave behind more offsprings and will have more variations.
Survival chances also depend on the nature of variations.
Series Z
Ans: Given;
P = + 1.5 D
We Know that;
P = 1/F
Or F = 1/P
F = 1/1.5
F = 0.67 m or 67 cm
+ve sign shows the lens is convex.
20. What do you mean by resistors connected in parallel ?
Ans: When resistors are connected in Parallel, it means they are placed Side-by- Side along a single path. In Parallel, the potential difference across the ends of conductor is same.
21. List the properties of magnetic lines of force.
Ans: Properties of Magnetic lines of force are:
(i) Magnetic lines of force start from the north pole and travel to the south pole outside the magnet.
(ii) They travel from South to North inside the magnet
(iii) They never intersect each other
(iv) Their magnitude decreases as we move away from the magnet.
22. What is combination reaction? Give one example.
Ans: A reaction in which two or more substances, elements or compounds combine to form single substance is called combination reaction.
Example of combination reaction:
CaO + CO2 ----------> CaCO3
23. Write down the structural formula of: (i)Ethane (ii) Pentane
Ans: (i) Ethane: CH3-CH3
(ii) Pentane: CH3-CH2-CH2-CH2-CH3
24. Why is sodium kept immersed in kerosene oil?
Ans: Sodium is kept immersed in kerosene oil because sodium reacts vigorously with both air and water.
Na + O2 _____> Na2O
Na2O + H2O _____> NaOH
25. Write down the functions of salivary amylase and pepsin.
Ans: Salivary amylase converts starch into maltose
Pepsin converts proteins into peptides
26. Why are some diabetic patients treated by giving insulin ?
Ans: The diabetic patients are not able to secrete insulin to regulate blood sugar.
Hence they are given insulin injections which helps them to lower blood sugar level.
27. Why is vegetative propagation practised for growing same types of plants ?
Ans: Vegetative propagation is practiced because:
i. It is a quicker and less difficult way.
ii. It can aid plant growth in areas where germination has failed.
iii. It can be used to propagate plants that don't generate viable seeds or produce a small quantity of seeds.
iv. It's a quick way to grow a lot of plants in a short amount of time.
v. Potato tubers and ginger rhizomes are two examples.
28. How is the sex of the child determined in human beings ?
Ans: The sex of child is determined by sex chromosomes. Males have XY chromosomes where as Females have XX chromosomes.
If the sperm with X chromosome fertilizes egg, The child will be female.
If the sperm with Y chromosome fertilizes egg, The child will be Male
Section-C
Ans: Hypermetropia means long sightedness. A person sees far off objects clearly but cant see nearby objects.
In hypermetropia, the days of light meet behind Retina.
It is treated by convex lens.
(i) What is the far point and near point of the human eye with normal vision?
Ans: Far point is maximum distance upto which an eye can see. It is infinite for normal eye.
Near Point is minimum distance upto which an eye can see. It is 25 cm for normal eye
(ii) What is meant by power of accommodation of the eye?
Ans: Power of accomodation means ability of eye to adjust its focal length to see objects at different distances. It is possible due to change in thickness of eye lens.
To see distant objects, the lens becomes thin. To see near objects, the lens becomes thick.
30. Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Give reasons in support of your answer.
Ans: Current will flow more easily through a thick wire because the resistance is inversely proportional to the area of cross-section of the wire. Which means when the area of cross section of the wire increases then resistance will decrease.
ii. The potential difference between the terminals of an electric heater is 60 V when it draws a current of 4 A from the source. What current will the heater draw if the potential difference is increased to 120 V?
Ans: Given,
Potential difference = 60 V Current = 4 A
Thus, Resistance(R) = V/I
R = 60/4
R = 15 Ohm.
Therefore resistance of heater is 15 Ohm.
Now, When Potential difference is increased to 120 V, the current will also increase but the resistance will remain same.
Thus New Current (I) = V/R
I = 120/15
I = 8 A
Therefore, 8A current will flow when Potential difference is increased to 120V.
31. (i) What is Right hand thumb rule ?
Ans: Right hand thumb rule helps determine Magnetic field around a straight current carrying conductor. If the thumb is placed in the direction of current, the fingers show the direction of magnetic field as shown in figure:
(ii) Draw magnetic field lines around a bar magnet.
Ans:
(i) What is the function of an earth wire ?
Ans: Earth wire is a wire with low resistance that prevents live wire overloading and current leakage through the ground.
A metallic body of high power rating electrical equipment is earthed by Earth wire that protects us from electric shocks.
(ii) When does an electric short circuit occur?
Ans: Electric short circuit occurs when the Live wire comes in contact with Neutral wire.
This can happen if the insulation around the wire gets removed
32. Write the balanced equation for the following reactions:
(a) Hydrogen + Chlorine → Hydrogen chloride
Ans: H2 + Cl2 -> 2HCl
(b) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride
Ans: 3BaCl2 + Al2(SO4)3 → 2AlCl3 + 3BaSO4
(c) Sodium + Water → Sodium hydroxide + Hydrogen
Ans: 2Na + 2H2O → 2NaOH + H2
Q. Describe Oxidation and Reduction reactions with examples.
Ans: Oxidation Reduction reaction is also known as redox reaction. It is the reaction where addition of oxygen/ removal of hydrogen or vice versa takes place simultaneously.
It is also defined as reaction where one substance looses electron and other substance gains electron
Examples of Redox reaction:
CuO + H2 ----------> Cu + H2O
Q. Describe Displacement Reactions with two examples.
Ans: The reaction in which one element takes place of another in a compound is called displacement reaction.
In a Displacement reaction, a more reactive element displaces a less reactive element.
Example of displacement reaction:
CuSO4 + Zn ----------> ZnSO4 + Cu
CuSO4 + Fe ----------> FeSO4 + Cu
Q. Decomposition reactions require energy either in the form of heat or light or electricity for breaking down the reactants. Write one example of each form.
Ans: The reaction in which a compound splits up into two or more simple substances is called decomposition reaction.
Examples:
Heat: CaCO3 -> CaO + CO2
Light: AgCl -> Ag + Cl2
Electricity: H2O -> H2 + O2
Q. Name the type of chemical reaction in the following equations:
i. CaO + H2O -> Ca(OH)2
Ans: Combination Reaction
ii. BaCl2 + Al2(SO4)3 -> AlCl3 + BaSO4
Ans: Double Displacement Reaction
iii. FeSO4 -> Fe2O3 + SO2 + SO3
Ans: Decomposition Reaction
33. Write down a note on Aqua Regia.
Ans: Aqua Regia is the mixture of Hydrochloric acid and Nitric acid in the proportion of 3:1. Aqua Regia dissolves metals like gold and silver in it
Q. Write down three properties of ionic compounds.
Ans: Ionic compounds are composed of Ions i.e Cations and Anions. E.g; NaCl
B. They are crystalline solids.
C. They have high Melting point and boiling points.
D. They are hard but brittle
34. What is an alkali? Write down two properties of alkali.
Ans: Alkali is a base which is dissolved in water.
Properties: i. It has pH of above 7 ii. It turns litmus paper blue
Q. Write down three uses of Washing Soda.
Ans: Washing Soda is Na2CO3.
Its uses are:
1. It is used to make glass 2. It is used to make soap 3. It is used to soften hard water.
35. Write down the names of different parts of human brain. Draw the labelled diagram of human brain.
Ans: The human brain is soft, whitish organ inside cranium. It is sorrounded by three membranes called meninges filled with cerebrospinal fluid.
The human brain is divided into three parts.
Parts: I. Forebrain (Prosencephalon): Contains Cerebrum, Olfactory Lobes & Diencephalon
II. Mid Brain (Mesencephalon)
III. Hind Brain (Rhombencephalon) Contains Cerebellum, Pons Varolii, Medulla Oblongata
Diagram:
Q. Write down the functions of the following human hormones: (i) Thyroxin (ii) Adrenaline
Ans: Thyroxine: It regulates metabolism of the body.
Adrenaline: Adrenaline is a rush hormone. It results in increase in heart beat, blood sugar and heavy breathing. It also dilates our blood vessels.
36. What is the importance of DNA copying in Reproduction?
Ans: DNA copying maintains body design and perfection in different generations of a species.
Error in DNA copying can lead to abnormalities in the population.
Q. What are the different methods of contraception?
Ans: contraception means prevention of fusion of gamates.
The different methods of contraception are:
I. Natural: It can be done by avoiding intercourse from 10th to 17th day of mensuration cycle.
II. Barrier method: Use of barriers such as condom, copper T
III. Oral: Use of medicine which prevent fertlization.
IV. Surgical: It includes vasectomy and tubectomy.
37. What is Biological Magnification? Will the levels of this magnification be different at different levels of the ecosystem ?
Ans: Biomagnification is defined as proportional increase of harmful chemical substances in higher trophic levels. E.g DDT.
Yes, the levels of magnification will be more at higher tropic levels.
Q. Why is the damage to the ozone layer a cause for concern ? What steps are being taken to limit this damage ?
Ans: Ozone is a molecule of oxygen (O3). It forms a layer in stratosphere and blocks Ultraviolet rays of sun from reaching earth. The Ultraviolet rays will kill living organisms by causing mutations. These rays can cause skin cancer, cataracts, and will destroy ecosystems. So Ozone is vital for all ecosystems on Earth because it protects the environment from the harmful effects of UV radiation.
Steps: i. Less use of CFC’s ii. Montreal Protocol
Section-D
Ans: Given;
H = 5 U = -25 F = 10 V = ? H = ?
We Know;
1/F = 1/V – 1/U
1/10 = 1/V – 1/-25
1/V = 1/10 – 1/25
1/V = 5 – 2/50
1/V = 3/50
V= 50/3
V = 16.7 cm
Now, Magnification (M) = H’/H = V/U
H’ = H.V/U
H’ = 5 x 16.7/ -25
H’ = - 3.3 cm
This shows Image is Real, Inverted and Diminished and 16.7 cm away from the lens on the same side as that of object.
Q. Describe the mirror formula and magnification in spherical mirrors.
Ans: Mirror Formula: Mirror formula is the relation between Object Distance (U), Image Distance (V) and focal length (F) of mirror.
It is given by,
1/V + 1/U = 1/F
Magnification: Magnification by spherical mirror is defined as ratio of height of image (h') to height of object (h), i.e,
M = h'/h = -V/U
39. (i) Explain the mechanism of clearing action of soaps.
Ans: Soaps are sodium or potassium salts of fatty acids. A molecule of soap contains two parts;
i. Hydrophobic long chain hydrocarbon
ii. Hydrophilic Polar group.
Mechanism of Action:
In water, the soap molecule dissociates and hydrocarbon part sticks with oils and dirt. The Polar group attaches to water. Thus micelles are formed which are washed away by water.
(ii) Explain the formation of scum when hard water is treated with soap.
Ans: Hard water contains high mineral content. The minerals react with soap molecules to form salts.
These salts form scum over surface of water.
Q. How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties ?
Ans: Ethanol is basic having pleasant smell where as ethanoic acid is acidic having vinegar smell.
Ethanol has no action on litmus paper, Ethanoic acid turns blue litmus red.
Ethanol doesn’t react with sodium bicarbonate, Ethanoic acid reacts with sodium bicarbonate.
40. (i) What is the role of saliva in the digestion of food ?
Ans: Saliva makes food moist which helps us to taste food and easy to swallow
It contains salivary amylase which convert starch to maltose.
It contains maltase, which convert maltose to glucose.
(ii) How are fats digested in our body?
Ans: Fats are mainly digested in duodenum. In duodenum, the food gets mixed with bile from liver and pancreatic juices from pancreas.
Bile helps to emulsify fats that break down large fat molecules into smaller droplets. This process is called Emulsification.
Pancreatic juices contain lipase which breaks down fats into fatty acid
(i) How is oxygen and carbon dioxide transported in human body?
Ans: The oxygen and carbon dioxide are transported in human beings by haemoglobin.
The haemoglobin is present in RBS's.
Oxygen is carried to the cells.
Carbon dioxide is carried away from the cells.
(ii) What would be the consequences of a deficiency of haemoglobin in our bodies?
Ans: Haemoglobin is found inside the RBC’s in the blood and carries oxygen to the body parts. Deficiency of haemoglobin causes anemia.
It leads to tiredness and weight loss.
