10th Science Quarterly Exam 2024 Question Paper with Solutions | Chennai District (English Medium)

10th Science Quarterly Exam 2024 - Original Question Paper with Solutions

Class: 10 Subject: Science Exam: Common Quarterly Examination - 2024-25 Max. Marks: 75 Time Allowed: 3.00 Hours

PART-I

Choose the correct answer. (12 x 1 = 12)

1. Impulse is equal to

1. Rate of change of momentum
2. Rate of force and time
3. Change of Momentum
4. Rate of change of mass

Answer: c) Change of Momentum

2. Atomicity of Phosphorous is

1. 4
2. 3
3. 6
4. 7

Answer: a) 4 (Phosphorus exists as P₄, so it is tetra-atomic).

3. Which one is referred as "Master Gland"?

1. Pineal Gland
2. Pituitary Gland
3. Thyroid Gland
4. Adrenal Gland

Answer: b) Pituitary Gland

4. In India domestic circuits are supplied with an alternating current of Potential

1. 230/220 V
2. 220/230 V
3. 230/240 V
4. 240/230 V

Answer: b) 220/230 V (Note: This question is ambiguously framed. The standard potential is 220 V and the frequency is 50 Hz. The fractional options are likely a printing error. The most appropriate answer contains the standard value of 220V).

5. Deliquescence is due to

1. Strong affinity to water
2. Less affinity to water
3. Strong hatred to water
4. Inertness to water

Answer: a) Strong affinity to water (Deliquescent substances absorb so much moisture from the air that they dissolve in it).

6. The ___ Units form the backbone of the DNA

1. 5 Carbon Sugar
2. Phosphate
3. Nitrogenous base
4. Sugar Phosphate

Answer: d) Sugar Phosphate (The DNA backbone is made of alternating sugar and phosphate groups).

7. Which of the following lens would you prefer to use while reading small letters found in a dictionary?

1. A convex lens of Focal length 5 cm
2. A concave lens of Focal length 5cm
3. A convex lens of Focal length 10 cm
4. A concave lens of Focal length 10 cm

Answer: a) A convex lens of Focal length 5 cm (A convex lens with a shorter focal length provides greater magnification).

8. Neon shows Zero electron affinity due to

1. Stable arrangement of neutrons
2. Stable configuration of electrons
3. Reduced size
4. Increased density

Answer: b) Stable configuration of electrons (Neon has a completely filled valence shell, making it very stable).

9. ___ is an instrument which records the electrical impulses, of brain

1. ECG
2. EGG
3. EEG
4. EGE

Answer: c) EEG (Electroencephalogram).

10. "Heart of Heart" is called

1. SA node
2. AV node
3. Purkinje fibres
4. Bundle of His

Answer: a) SA node (Sinoatrial node, as it is the natural pacemaker of the heart).

11. Nerve cells donot Possess

1. Neurilemma
2. Sarcolemma
3. Axon
4. Dentrites

Answer: b) Sarcolemma (Sarcolemma is the cell membrane of a muscle cell, not a nerve cell).

12. Across the period, ionic radii

1. Increase and then Decrease
2. Increases
3. Decreases
4. Remains constant

Answer: c) Decreases (Ionic radii generally decrease across a period due to increased nuclear charge).

PART - II

Answer any seven questions. Q.No. 22 is compulsory. (7 x 2 = 14)

13. Define: Co efficient of real expansion, and mention its Units.

Definition: The coefficient of real expansion is defined as the ratio of the true rise in the volume of the liquid per degree rise in temperature to its unit volume.
Unit: The SI unit of the coefficient of real expansion is K⁻¹ (per Kelvin). It can also be expressed as °C⁻¹ (per degree Celsius).

14. What is Rust? Give the equation for the Formulation of Rust.

Rust: Rust is a reddish-brown hydrated ferric oxide formed on the surface of iron or its alloys when exposed to air and moisture. It is a form of corrosion.
Equation: 4Fe + 3O₂ + xH₂O → 2Fe₂O₃·xH₂O (Hydrated ferric oxide)

15. Why is Sinoatrial node Called as Pacemaker of Heart.

The Sinoatrial (SA) node is called the pacemaker of the heart because it has the unique ability to spontaneously generate electrical impulses at the highest rate. These impulses initiate the heartbeat and set the pace for the heart's contractions, ensuring a regular rhythm.

16. Match the items in column I to items in Column II

• i) Electric Current - e) Ampere
• ii) Potential difference - a) Volt
• iii) Specific resistance - b) Ohm meter
• iv) Electrical energy - d) Joule

17. Why the Relative molecular mass has no Unit?

Relative molecular mass is a ratio. It is defined as the ratio of the mass of one molecule of a substance to 1/12th the mass of a Carbon-12 atom. Since it is a ratio of two similar quantities (masses), the units cancel out, making it a dimensionless quantity.

18. What do you understand by the term Phenotype and Genotype?

Genotype: It is the genetic makeup of an organism. It represents the combination of alleles that an individual possesses for a particular trait (e.g., TT, Tt, tt).
Phenotype: It is the observable physical or external characteristic of an organism, which is determined by its genotype and environmental factors (e.g., tall, dwarf).

19. Difference between Systemic Circulation and Pulmonary Circulation?

Systemic Circulation: This is the circulation of oxygenated blood from the left ventricle of the heart to all parts of the body, and the return of deoxygenated blood to the right atrium.
Pulmonary Circulation: This is the circulation of deoxygenated blood from the right ventricle of the heart to the lungs for oxygenation, and the return of oxygenated blood to the left atrium.

20. While catching a cricket Ball, the Fielder lowers his hands Backwards. Why?

According to Newton's second law of motion, Force = Change in momentum / time (F = Δp/Δt). By lowering his hands, the fielder increases the time (Δt) over which the ball's momentum is brought to zero. This increase in time reduces the magnitude of the impact force (F) on the fielder's hands, preventing injury.

21. What is respiratory Quotient?

The Respiratory Quotient (RQ) is the ratio of the volume of carbon dioxide (CO₂) evolved to the volume of oxygen (O₂) consumed during respiration over a period of time.
Formula: RQ = Volume of CO₂ released / Volume of O₂ consumed

22. Calculate the number of water Molecules present in one drop of water which weights 0.18g. (Compulsory)

Given: Mass of a drop of water = 0.18 g
Molar mass of water (H₂O) = (2 × 1.008) + 16.00 = 18.016 g/mol ≈ 18 g/mol
Number of moles (n) = Given mass / Molar mass = 0.18 g / 18 g/mol = 0.01 mol
Number of molecules = Number of moles × Avogadro's number (Nₐ)
Number of molecules = 0.01 × 6.022 × 10²³
Number of molecules = 6.022 × 10²¹ molecules

PART - III

Answer any seven questions. Q.No: 32 is compulsory. (7 x 4 = 28)

23. a) Differentiate Mass and Weight (any two)

1. Definition: Mass is the amount of matter in an object. Weight is the gravitational force exerted on an object.
2. Constancy: Mass is constant everywhere. Weight varies with location (changes with gravity).
3. SI Unit: The SI unit of mass is kilogram (kg). The SI unit of weight is newton (N).
4. Measurement: Mass is measured using a physical balance. Weight is measured using a spring balance.

b) Write any two properties of Light

1. Rectilinear Propagation: Light travels in a straight line in a uniform medium.
2. Reflection: Light bounces back when it strikes a polished surface.
3. Refraction: Light bends when it travels from one medium to another.
4. Speed: Light travels at a very high speed of approximately 3 × 10⁸ m/s in a vacuum.

24. a) Why are traffic signals Red in Colour?

Traffic signals are red because red light has the longest wavelength among all the colors in the visible spectrum. According to Rayleigh's law of scattering, light with a longer wavelength is scattered the least by atmospheric particles like fog, smoke, and rain. This minimal scattering allows the red light to travel the longest distance without losing intensity, making it visible from far away, which is crucial for safety.

b) What is Power of Accommodation Eye?

The power of accommodation of the eye is the ability of the eye lens to change its focal length with the help of ciliary muscles. This adjustment allows the eye to focus on objects at varying distances, from near to far, and form a clear image on the retina.

25. a) Will the cool drinks give more fizz at the top of the hills or at the foot. Explain.

Cool drinks will give more fizz at the top of the hills.
Explanation: The fizz in cool drinks is due to dissolved carbon dioxide (CO₂) gas. According to Henry's Law, the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid. At the top of a hill, the atmospheric pressure is lower than at the foot. When the bottle is opened, the lower external pressure causes the dissolved CO₂ to come out of the solution much more rapidly, resulting in more fizz.

b) CaCO₃ → CaO + CO₂
i) How many moles of Calcium carbonate are involved in this reaction
ii) How many moles of CO₂ are their in this equation

For the balanced chemical equation: CaCO₃ → CaO + CO₂
i) The stoichiometric coefficient before Calcium Carbonate (CaCO₃) is 1. Therefore, 1 mole of Calcium carbonate is involved.
ii) The stoichiometric coefficient before Carbon Dioxide (CO₂) is 1. Therefore, 1 mole of CO₂ is produced.

26. Differentiate between hygroscopic substances and deliquescence substances.

1. Hygroscopic substances absorb moisture from the atmosphere without changing their physical state. They just become damp.
   Example: Concentrated Sulphuric acid, quicklime (CaO).
2. Deliquescent substances absorb so much moisture from the atmosphere that they dissolve in the absorbed water and turn into a solution. They change their physical state from solid to liquid.
   Example: Sodium hydroxide (NaOH), calcium chloride (CaCl₂).
3. All deliquescent substances are hygroscopic, but not all hygroscopic substances are deliquescent.

28. a) Write the Chargaff rule of DNA base pairing.

Chargaff's rules of DNA base pairing state that:

1. The amount of adenine (A) is always equal to the amount of thymine (T), and the amount of guanine (G) is always equal to the amount of cytosine (C). (A=T and G=C).
2. The total amount of purines (A + G) is always equal to the total amount of pyrimidines (T + C).

b) Why the mature RBC in Mammals do not have Cell Organelles?

Mature mammalian Red Blood Cells (RBCs) lack a nucleus and other cell organelles like mitochondria for two main reasons:

1. To Maximize Hemoglobin Content: The absence of organelles provides maximum intracellular space for hemoglobin, the protein that carries oxygen. This allows each RBC to transport the maximum amount of oxygen.
2. To Prevent Oxygen Consumption: Without mitochondria, RBCs do not perform aerobic respiration. This ensures that the oxygen they carry is delivered to the body tissues and not consumed by the RBC itself.

29. The electronic configuration of metal 'A' is 2, 8, 18, 1 the metal 'A' with Con. H₂SO₄ forms C and D along with water. 'D' is a gaseous compound. Find A, B, C and D.

Finding A: The electronic configuration is 2, 8, 18, 1. The total number of electrons is 2+8+18+1 = 29. The element with atomic number 29 is Copper (Cu). So, A = Copper (Cu).
The Reaction: Copper reacts with concentrated Sulphuric acid (H₂SO₄) upon heating. Cu (A) + 2H₂SO₄ (conc.) → CuSO₄ (C) + SO₂ (D) + 2H₂O
Finding C and D: The products are copper sulphate (C), sulphur dioxide (D), and water. The question states 'D' is a gaseous compound. Sulphur dioxide (SO₂) is a gas. So, C = Copper Sulphate (CuSO₄) and D = Sulphur Dioxide (SO₂).
(Note: The question asks for 'B', which is not mentioned in the reaction setup. Assuming 'B' is the reactant H₂SO₄, then B = Concentrated Sulphuric Acid).

30. a) What is Guttation?

Guttation is the process of exudation of water in the form of droplets from the pores (hydathodes) on the margins of leaves. It occurs when root pressure is high and transpiration rate is low, typically during early mornings or humid nights.

b) Where are Estrogens Produced? What is the role of Estrogens in the Human body?

Production: Estrogens are primarily produced by the developing follicles in the ovaries. Small amounts are also produced by the adrenal cortex and placenta during pregnancy.
Role of Estrogens:

• Development of female secondary sexual characteristics (e.g., breast development, pubic hair).
• Maturation of the uterine lining (endometrium) during the menstrual cycle.
• Regulation of the menstrual cycle.
• Involved in the development and maintenance of the female reproductive system.

31. Identify whether the statement are True or False. Correct the False statement.

i) An anticoagulant present in the saliva of leech is called heparin.
False. The anticoagulant present in the saliva of a leech is called Hirudin.

ii) Cerebrum controls the voluntary actions of our body.
True.

b) Define: Reflex arc

A reflex arc is the neural pathway that mediates a reflex action. It includes a sensory receptor, a sensory neuron, an interneuron (in the spinal cord), a motor neuron, and an effector (muscle or gland). This pathway allows for rapid, involuntary responses to stimuli without involving conscious thought from the brain.

32. Calculate the coefficient of Cubical expansion of Zine bar, whose volume is increased 0.25 m³ from 0.3m³ due to the change in temperature of 50k (Compulsory)

(Note: The question wording "increased 0.25 m³ from 0.3m³" is ambiguous. It can be interpreted as Initial Volume = 0.3 m³ and Change in Volume = 0.25 m³. We will proceed with this interpretation.)
Given:

• Initial Volume (V) = 0.3 m³
• Change in Volume (ΔV) = 0.25 m³
• Change in Temperature (ΔT) = 50 K

Formula for Coefficient of Cubical Expansion (αᵥ):
αᵥ = (Change in Volume) / (Initial Volume × Change in Temperature)
αᵥ = ΔV / (V × ΔT)
Calculation:
αᵥ = 0.25 / (0.3 × 50)
αᵥ = 0.25 / 15
αᵥ ≈ 0.01667 K⁻¹
The coefficient of cubical expansion of the Zinc bar is approximately 0.0167 K⁻¹.

PART - IV

Answer all the questions in detail. (3 x 7 = 21)

33. a) "Wearing helmet and fastening the seat belt is highly recommended, for safe Journey". Justify your answer using Newton's Laws of Motion.

Seat Belt and Newton's First Law (Inertia): When a car stops suddenly, the passenger's body continues to move forward due to inertia of motion. The seat belt applies an opposing force to the passenger, preventing them from colliding with the dashboard or windshield and causing serious injury. It safely brings the body to rest along with the car.

Helmet and Newton's Second Law (Force): According to Newton's Second Law, Force (F) is the rate of change of momentum (F = Δp/Δt). During an accident, the head's momentum changes rapidly upon impact. The soft padding inside a helmet increases the time of impact (Δt). By increasing the time, the magnitude of the impact force (F) on the head is significantly reduced, thus preventing or minimizing head injury.

b) State Newton's Third Law.

Newton's Third Law of Motion: For every action, there is an equal and opposite reaction. It states that forces always occur in pairs, and that for every force exerted by one object on a second object, the second object exerts a force that is equal in magnitude and opposite in direction on the first object.

c) Give any two examples for moment of a Couple.

1. Turning a steering wheel of a car.
2. Opening or closing a water tap.
3. Winding a key in a clock.

(OR)

a) Differentiate series and Parallel circuit (any two)

1. Path for Current: In a series circuit, there is only one path for the current to flow. In a parallel circuit, there are multiple paths for the current.
2. Current: In a series circuit, the current is the same through all components. In a parallel circuit, the current divides among the branches.
3. Voltage: In a series circuit, the total voltage is divided among the components. In a parallel circuit, the voltage is the same across all components.
4. Equivalent Resistance: In a series circuit, the equivalent resistance (Rₛ = R₁ + R₂ + ...) is greater than the largest individual resistance. In a parallel circuit, the equivalent resistance (1/Rₚ = 1/R₁ + 1/R₂ + ...) is less than the smallest individual resistance.

b) State. Joule's law of Heating.

Joule's Law of Heating: It states that the heat (H) produced in a conductor is directly proportional to:

1. the square of the current (I²) flowing through it,
2. the resistance (R) of the conductor, and
3. the time (t) for which the current flows.

Formula: H = I²Rt

c) What is the role of the Earthwire domestic circuits.

The earth wire is a safety device in domestic circuits. Its primary role is to protect users from electric shock. If a fault causes the live wire to touch the metallic casing of an appliance, the earth wire provides a low-resistance path for the large current to flow directly to the ground. This causes a massive surge of current, which blows the fuse or trips the circuit breaker, disconnecting the power supply and making the appliance safe to touch.

34. a) Give the salient features of Modern atomic theory.

• The atom is no longer considered indivisible. It is made of subatomic particles: protons, neutrons, and electrons.
• Atoms of the same element may have different atomic masses. These are called isotopes (e.g., ¹²C, ¹³C, ¹⁴C).
• Atoms of different elements may have the same atomic mass. These are called isobars (e.g., ⁴⁰Ar, ⁴⁰K, ⁴⁰Ca).
• The atom is the smallest particle that takes part in a chemical reaction.
• The mass of an atom can be converted into energy according to Einstein's equation, E = mc².

b) Identify the bond between the 'H' and 'F' in HF Molecule

The bond between Hydrogen (H) and Fluorine (F) in an HF molecule is a Polar Covalent Bond.
Explanation: Fluorine is the most electronegative element, and Hydrogen has a much lower electronegativity. This large difference in electronegativity causes the shared pair of electrons to be pulled much closer to the Fluorine atom, creating a partial negative charge (δ-) on Fluorine and a partial positive charge (δ+) on Hydrogen. Due to this charge separation, the bond is highly polar. (At this level, sometimes described as having significant ionic character).

c) Name the Acid that renders Aluminium Passive.

The acid that renders Aluminium passive is Concentrated Nitric Acid (HNO₃). It forms a thin, non-reactive, protective layer of aluminium oxide (Al₂O₃) on the surface of the metal, which prevents it from further reaction.

(OR)

a) What happens when MgSO₄.7H₂O is heated? Write the appropriate equation.

When Magnesium Sulphate Heptahydrate (MgSO₄·7H₂O), also known as Epsom salt, is heated, it loses its water of crystallization and becomes anhydrous magnesium sulphate.
Equation:
MgSO₄·7H₂O(s) →_Heat MgSO₄(s) + 7H₂O(g)
(Magnesium Sulphate Heptahydrate) → (Anhydrous Magnesium Sulphate) + (Water Vapour)

b) Write notes on Various features affecting solubility.

The main features affecting the solubility of a solute in a solvent are:

• Nature of Solute and Solvent: Based on the principle "like dissolves like". Polar solutes (like salt) dissolve in polar solvents (like water), while non-polar solutes (like oil) dissolve in non-polar solvents (like hexane).
• Temperature: For most solid solutes in liquid solvents, solubility increases with an increase in temperature. For gaseous solutes, solubility decreases with an increase in temperature.
• Pressure: Pressure has a significant effect only on the solubility of gases in liquids. According to Henry's law, the solubility of a gas increases with an increase in pressure.

35. a) Luteal Phase of the Menstrual cycle is also called the secretory Phase. Give Reason.

The Luteal Phase is called the Secretory Phase because, during this phase, the corpus luteum (formed from the ruptured ovarian follicle) secretes large amounts of the hormone progesterone. Progesterone stimulates the glands of the uterine wall (endometrium) to secrete a nutrient-rich fluid. This makes the endometrium thick, soft, and ready for the implantation of a fertilized ovum, hence the term 'secretory'.

b) Define: Triple Fusion.

Triple fusion is a process that occurs in the embryo sac of flowering plants (angiosperms). It is the fusion of one of the male gametes (n) with the diploid secondary nucleus (2n), which is formed by the fusion of two polar nuclei. This fusion results in the formation of a triploid (3n) Primary Endosperm Nucleus (PEN), which develops into the endosperm, the nutritive tissue for the developing embryo.

c) Why family planning methods are not adopted by all the people of our country?

Family planning methods are not universally adopted in our country due to a combination of factors:

• Lack of Awareness and Education: Insufficient knowledge about contraception and its benefits, especially in rural areas.
• Social and Religious Beliefs: Certain cultural and religious norms may discourage the use of contraceptives.
• Desire for a Male Child: The preference for a son leads couples to have more children until a male heir is born.
• High Infant Mortality Rate: In some regions, couples have more children with the fear that not all will survive to adulthood.
• Inaccessibility: Lack of easy access to healthcare facilities and contraceptive methods in remote areas.

(OR)

a) List out the Parasitic adaptations of Leech.

The parasitic adaptations of a leech include:

• Anterior and Posterior Suckers: Used for firm attachment to the host's body and for locomotion.
• Three Jaws: The anterior sucker contains three tiny jaws that make a painless, Y-shaped incision in the host's skin.
• Hirudin Secretion: The salivary glands secrete hirudin, a powerful anticoagulant, which prevents the host's blood from clotting, ensuring a continuous supply of blood.
• Large Crop: The digestive tract has a large crop with many chambers (diverticula) to store a large volume of blood, which can be digested slowly over several months.

b) What are the structures involved in the Protection of Brain.

The brain is protected by three main structures:

1. The Cranium (Skull): The bony box of the skull provides a hard, rigid outer covering that protects the brain from physical injury.
2. The Meninges: These are three protective membranes that lie between the skull and the brain. From outermost to innermost, they are:
   • Dura Mater: The tough, fibrous outer layer.
   • Arachnoid Mater: The web-like middle layer.
   • Pia Mater: The delicate inner layer that adheres to the surface of the brain.
3. Cerebrospinal Fluid (CSF): This fluid is found in the space between the arachnoid and pia mater (subarachnoid space) and within the ventricles of the brain. It acts as a shock absorber, protecting the brain from jolts and impacts. It also provides nutrients and removes waste.