10th Science - Quarterly Exam 2024 - Original Question Paper | Theni District (English Medium)
Part - I (12 x 1 = 12)
i) Answer all the questions.
ii) Choose the most appropriate answer from the given 4 alternatives and write the option code and the corresponding answer.
1)Which is formed during anaerobic respiration?
2)The body of leech has
3)Which one of the following shows correct composition of blood
4)Bipolar neurons are found in
5)Which one is referred as "Master Gland"?
6)If the Earth shrinks to 50% of its real radius its mass remaining the same, the weight of a body on the Earth will
Explanation: Weight (W) is proportional to gravitational acceleration (g), and g = GM/R². If R becomes R/2, the new g' = GM / (R/2)² = 4(GM/R²) = 4g. The new weight W' = 4W. The increase is W' - W = 3W. Percentage increase = (3W/W) × 100% = 300%.
7)Where should an object be placed so that a real and inverted image of same size is obtained by a convex lens
8)If a substance is heated or cooled, the change in mass of that substance is
9)SI unit of resistance is
10)The volume occupied by 1 mole of a diatomic gas at S.T.P is
11)The process of coating the surface of metal with a thin layer of zinc is called
12)Which of the following is the universal solvent?
Part - II (7 x 2 = 14)
Answer any 7 questions.
13)Define inertia. Give its classification.
Classification:
- Inertia of rest: The resistance of a body to change its state of rest.
- Inertia of motion: The resistance of a body to change its state of motion.
- Inertia of direction: The resistance of a body to change its direction of motion.
14)Define dispersion of light.
15)State Boyle's law.
Mathematically, P ∝ 1/V (at constant T and n).
or PV = constant.
16)What happens to the resistance, as the conductor is made thicker?
17)What is Molar volume of a gas?
18)What is rust? Give the equation for formation of rust.
Equation: 4Fe + 3O₂ + xH₂O → 2Fe₂O₃.xH₂O (Hydrated ferric oxide)
19)What is aqueous and non-aqueous solution?
- Aqueous Solution: A solution in which water acts as the solvent is called an aqueous solution. Example: Sugar dissolved in water.
- Non-aqueous Solution: A solution in which any liquid other than water acts as the solvent is called a non-aqueous solution. Example: Sulphur dissolved in carbon disulphide.
20)Why should the light dependent reaction occur before the light independent reaction?
21)What does CNS stand for?
22)What is the importance of valves in the heart?
Part - III (7 x 4 = 28)
Answer any 7 questions. (Q.No.32 is compulsory)
23)A pure tall plant (TT) is crossed with pure dwarf plant (tt), what would be the F1 and F2 generations? Explain.
Parental Generation (P): Pure Tall (TT) × Pure Dwarf (tt)
Gametes: T from tall, t from dwarf
F1 Generation: All offspring will have the genotype Tt. Since 'T' (tall) is dominant over 't' (dwarf), all plants in the F1 generation will be tall (heterozygous tall).
Self-pollination of F1 generation: Tt × Tt
Gametes from F1: T and t from both parents
F2 Generation: The cross results in the following genotypes:
- TT (Homozygous Tall)
- Tt (Heterozygous Tall)
- Tt (Heterozygous Tall)
- tt (Homozygous Dwarf)
Genotypic Ratio: 1 (TT) : 2 (Tt) : 1 (tt)
Phenotypic Ratio: 3 (Tall) : 1 (Dwarf)
24)A 100 watt electric bulb is used for 5 hours daily and four 60 watt bulbs are used for 5 hours daily. Calculate the energy consumed (in kWh) in the month of January.
Given: Number of days in January = 31 days.
Energy consumed by the 100 W bulb:
- Power (P1) = 100 W = 0.1 kW
- Time (t) = 5 hours/day
- Energy (E1) = P1 × t × days = 0.1 kW × 5 h × 31 days = 15.5 kWh
Energy consumed by the four 60 W bulbs:
- Total Power (P2) = 4 × 60 W = 240 W = 0.24 kW
- Time (t) = 5 hours/day
- Energy (E2) = P2 × t × days = 0.24 kW × 5 h × 31 days = 37.2 kWh
Total Energy Consumed in January:
- Total Energy (E) = E1 + E2 = 15.5 kWh + 37.2 kWh = 52.7 kWh
25)Susan's father feels very tired and frequently urinates. After clinical diagnosis he was advised to take an injection daily to maintain his blood glucose level. What would be the possible cause for this? Suggest preventive measures.
Possible Cause: The symptoms of feeling very tired (fatigue) and frequent urination (polyuria) are classic signs of Diabetes Mellitus. This condition is caused by the insufficient production or inefficient use of the hormone insulin, which leads to high blood glucose levels. The daily injection is likely an insulin injection to regulate his blood sugar.
Preventive Measures:
- Dietary Management: Following a balanced diet low in sugar and carbohydrates, and rich in fiber.
- Regular Exercise: Engaging in physical activities like walking, jogging, or yoga helps in managing blood glucose levels.
- Regular Monitoring: Regularly checking blood sugar levels to keep them within the target range.
- Medication Adherence: Taking the prescribed medication (like insulin) regularly and on time.
26)"Wearing helmet and fastening the seat belt is highly recommended for safe journey". Justify your answer using Newton's laws of motion.
- According to this law, a body in motion will remain in motion with the same speed and in the same direction unless acted upon by an external force.
- When a person is in a moving vehicle, their body is also in a state of motion.
- If the vehicle stops suddenly (e.g., in an accident), the person's body continues to move forward due to inertia.
- A seat belt applies an external force to the torso, slowing it down with the car and preventing the person from hitting the dashboard or windshield.
- Similarly, a helmet protects the head. In a bike accident, the rider might be thrown off. The helmet provides a protective layer that absorbs the impact force when the head hits the ground, preventing severe injury.
27)An object is placed at a distance 20cm from a convex lens of focal length 10cm. Find the image distance and nature of the image.
Given:
Object distance (u) = -20 cm (by convention)
Focal length (f) = +10 cm (for a convex lens)
Using the lens formula: 1/f = 1/v - 1/u
Substituting the values:
1/10 = 1/v - 1/(-20)
1/10 = 1/v + 1/20
Rearranging for 1/v:
1/v = 1/10 - 1/20
1/v = (2 - 1) / 20
1/v = 1/20
Image distance (v) = +20 cm
Nature of the image:
- Since 'v' is positive, the image is formed on the other side of the lens and is a real image.
- Real images are always inverted.
- Since the object is placed at 2f (2 × 10 cm = 20 cm), the image is also formed at 2f and will be of the same size as the object.
28)Write notes on various factors affecting solubility.
- Nature of Solute and Solvent: The principle "like dissolves like" applies. Polar solutes (like salt) dissolve in polar solvents (like water), while non-polar solutes (like oil) dissolve in non-polar solvents (like benzene).
- Temperature:
- For most solid solutes in a liquid solvent, solubility increases with an increase in temperature.
- For gaseous solutes in a liquid solvent, solubility decreases with an increase in temperature.
- Pressure:
- Pressure has a negligible effect on the solubility of solids and liquids.
- For gaseous solutes, solubility is directly proportional to the pressure of the gas above the liquid (Henry's Law). Increasing pressure increases the solubility of a gas.
29) a) Calculate the number of moles in 27 grams of aluminium. b) Calculate the gram molecular mass of CO₂.
a) Number of moles in 27 g of aluminium:
- Molar mass of Aluminium (Al) = 27 g/mol
- Given mass = 27 g
- Number of moles = Given mass / Molar mass
- Number of moles = 27 g / 27 g/mol = 1 mole
b) Gram molecular mass of CO₂:
- Atomic mass of Carbon (C) = 12 u
- Atomic mass of Oxygen (O) = 16 u
- Gram molecular mass of CO₂ = (1 × Atomic mass of C) + (2 × Atomic mass of O)
- Gram molecular mass = (1 × 12) + (2 × 16) = 12 + 32 = 44 g/mol
30) a) Mention the two cases in which there will be no Doppler effect in sound b) What is stellar energy.
a) Cases with no Doppler effect:
- When both the source of sound and the listener are at rest.
- When the source and the listener move in such a way that the distance between them remains constant.
b) Stellar Energy:
Stellar energy is the energy radiated by stars, including our Sun. This energy is generated in the core of the star through a process called nuclear fusion. In this process, lighter atomic nuclei (primarily hydrogen) fuse together under immense temperature and pressure to form heavier nuclei (like helium), releasing a tremendous amount of energy in the form of light and heat.
31)List any four properties light.
- Rectilinear Propagation of Light: Light travels in a straight line in a homogenous medium.
- Reflection: The bouncing back of light when it strikes a polished surface.
- Refraction: The bending of light as it passes from one medium to another.
- Dispersion: The splitting of white light into its constituent colours.
32)(Compulsory) The electronic configuration of metal A is 2,8,18,1. The metal A when exposed to air and moisture forms B a green layered compound. A with con.H₂SO₄ forms C and D along with water. D is gaseous compound. Find A,B,C and D.
- The electronic configuration 2, 8, 18, 1 corresponds to a total of 29 electrons. The element with atomic number 29 is Copper.
A = Copper (Cu) - When copper is exposed to air (O₂, CO₂) and moisture (H₂O), it forms a green layer of basic copper carbonate.
B = Basic Copper Carbonate (CuCO₃.Cu(OH)₂) - Copper reacts with hot concentrated sulphuric acid (con.H₂SO₄) to form copper sulphate (C), sulphur dioxide gas (D), and water.
The reaction is: Cu + 2H₂SO₄(conc) → CuSO₄ + SO₂↑ + 2H₂O - C = Copper Sulphate (CuSO₄)
- D = Sulphur dioxide (SO₂)
Part - IV (3 x 7 = 21)
Answer all the questions.
33) a) Define Mole and Give the salient features of "Modern atomic theory".
a) Mole: A mole is defined as the amount of substance that contains as many elementary entities (atoms, molecules, ions, or other particles) as there are atoms in exactly 12 grams of the Carbon-12 isotope. This number is Avogadro's number, approximately 6.022 × 10²³ entities per mole.
Salient Features of Modern Atomic Theory:
- Atom is no longer indivisible: An atom is divisible and consists of subatomic particles: protons, neutrons, and electrons.
- Atoms of the same element may not be similar: The existence of isotopes (atoms of the same element with different mass numbers, e.g., ¹H, ²H, ³H) proves this.
- Atoms of different elements may be similar: The existence of isobars (atoms of different elements with the same mass number, e.g., ⁴⁰Ar, ⁴⁰K, ⁴⁰Ca) proves this.
- Atom is the smallest particle in a chemical reaction: An atom is the smallest unit of matter that takes part in a chemical reaction.
- Mass can be converted into energy: According to Einstein's equation, E = mc², the mass of an atom can be converted into energy, and vice-versa.
b) i) State the reason for addition of caustic alkali to bauxite ore during purification of bauxite.
ii) Along with cryolite and alumina, another substance is added to the electrolyte mixture. Name the substance and give one reason for the addition.
b) i) Reason for adding caustic alkali (NaOH):
Caustic alkali (sodium hydroxide) is added to bauxite ore (impure Al₂O₃) during the Baeyer's process. The reason is to selectively dissolve the aluminium oxide, converting it into soluble sodium aluminate, while leaving behind the insoluble impurities like ferric oxide (Fe₂O₃) and silica (SiO₂). This allows for the separation of pure alumina from the impurities.
The reaction is: Al₂O₃.2H₂O (s) + 2NaOH (aq) → 2NaAlO₂ (aq) + 3H₂O (l)
ii) Additional substance in electrolyte mixture:
- Name of the substance: Fluorspar (CaF₂)
- Reason for addition: It is added to the electrolyte mixture (molten alumina and cryolite) during the Hall-Héroult process for two main reasons:
- It further lowers the melting point of the electrolyte mixture (below 1000 °C).
- It increases the electrical conductivity of the electrolyte.
34)
a) Differentiate the following
i) Monocot root and Dicot root
ii) Aerobic and Anaerobic respiration
a) i) Differentiating Monocot root and Dicot root
| Feature | Monocot Root | Dicot Root |
|---|---|---|
| Xylem Bundles | Polyarch (more than six bundles) | Tetrarch (four bundles) |
| Pith | Large and well-developed at the center | Small or absent |
| Secondary Growth | Absent | Present (due to cambium) |
| Cortex | Wide | Comparatively narrow |
a) ii) Differentiating Aerobic and Anaerobic respiration
| Feature | Aerobic Respiration | Anaerobic Respiration |
|---|---|---|
| Oxygen | Requires oxygen | Does not require oxygen |
| Location | Cytoplasm and Mitochondria | Only in Cytoplasm |
| End Products | Carbon dioxide, Water, ATP | Ethyl alcohol or Lactic acid, CO₂, ATP |
| Energy Yield | High (36/38 ATP molecules) | Low (2 ATP molecules) |
b) i) Explain the male reproductive system of rabbit with a labelled diagram.
ii) What is bolting? How can it be induced artificially?
b) i) Male Reproductive System of Rabbit:
The male reproductive system of a rabbit consists of the testes, epididymis, vas deferens, urethra, and accessory glands. (Students should draw a labelled diagram).
- Testes: A pair of testes are the primary reproductive organs that produce sperm and the male hormone testosterone. They are located in scrotal sacs outside the abdominal cavity to maintain a lower temperature necessary for sperm production.
- Epididymis: A highly coiled tube where sperm mature and are stored temporarily.
- Vas Deferens: A tube that carries sperm from the epididymis to the urethra.
- Urethra: A common passage for both urine and semen. It passes through the penis.
- Accessory Glands: These include the prostate gland, Cowper's gland, and perineal glands. They secrete fluids that mix with sperm to form semen. This fluid provides nourishment and a medium for sperm to swim.
b) ii) Bolting:
Bolting is the premature elongation of the internodes followed by flowering in plants that are typically rosette-forming or biennial (which flower in their second year). This often occurs due to specific environmental triggers like temperature or day length changes.
Artificial Induction: Bolting can be induced artificially by the application of the plant hormone Gibberellin. Spraying a rosette plant with gibberellins can stimulate rapid stem elongation and flowering, bypassing the need for natural stimuli like cold treatment (vernalization).
35)
a) i) State Newton's laws of motion.
ii) Deduce the equation of a force using Newton's second law of motion.
a) i) Newton's Laws of Motion:
- First Law (Law of Inertia): Every body continues to be in its state of rest or of uniform motion along a straight line unless it is acted upon by an external force to change the state.
- Second Law (Law of Force): The rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts.
- Third Law (Law of Action and Reaction): For every action, there is an equal and opposite reaction.
a) ii) Deduction of F = ma:
According to Newton's second law, force (F) is directly proportional to the rate of change of momentum.
Let a body of mass 'm' be moving with an initial velocity 'u'. Let a force 'F' act on it for a time 't', changing its velocity to 'v'.
- Initial momentum (p₁) = mu
- Final momentum (p₂) = mv
- Change in momentum = p₂ - p₁ = mv - mu = m(v - u)
- Rate of change of momentum = (Change in momentum) / time = m(v - u) / t
From the second law: F ∝ m(v - u) / t
We know that acceleration (a) = (v - u) / t (rate of change of velocity).
Substituting this, we get: F ∝ ma
To remove the proportionality, we introduce a constant, k: F = kma
The unit of force is chosen such that the value of the constant k becomes 1. One Newton is defined as the force required to produce an acceleration of 1 m/s² in a body of mass 1 kg. Thus, k = 1.
Therefore, F = ma.
b) i) Explain the construction and working of a 'Compound Microscope'
ii) Why does the sky appear in blue colour?
b) i) Compound Microscope:
Construction: A compound microscope consists of two convex lenses:
- Objective Lens: A convex lens with a short focal length, placed near the object being viewed.
- Eyepiece (Ocular lens): A convex lens with a longer focal length, placed near the observer's eye.
- Both lenses are mounted in a tube with an arrangement to adjust the distance between them.
Working:
- The object is placed just beyond the focal point of the objective lens.
- The objective lens forms a real, inverted, and magnified image (I₁) inside the tube.
- This first image (I₁) acts as the object for the eyepiece.
- The eyepiece is adjusted so that the image I₁ falls within its focal length.
- The eyepiece then acts as a simple microscope (magnifying glass) and forms a final, virtual, enlarged, and inverted image (I₂) at the near point of the eye.
b) ii) Why the Sky Appears Blue:
The blue colour of the sky is due to a phenomenon called Rayleigh scattering.
- Sunlight is composed of a spectrum of colours (VIBGYOR).
- When sunlight enters the Earth's atmosphere, it interacts with the tiny gas molecules and dust particles present in the air.
- According to Rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of the wavelength of light (Scattering ∝ 1/λ⁴).
- This means shorter wavelengths (like blue and violet) are scattered much more strongly than longer wavelengths (like red and orange).
- Although violet is scattered the most, our eyes are more sensitive to blue light. Therefore, when we look at the sky, we see this scattered blue light, making the sky appear blue.