10th Science - Quarterly Exam 2024 - Original Question Paper | Coimbatore District (English Medium)
This post provides the complete solutions for the 10th Standard Science Quarterly Examination paper from 2024, conducted in the Coimbatore District. Students can use this to verify their answers and prepare for future exams.
PART I - SOLUTIONS (12 × 1 = 12)
NOTE: (i) Answer all the questions. (ii) Choose the most appropriate answer from the given four alternatives and write the option code and the corresponding Answer.
1. Newton's III law is applicable .........
(c) both a & b
2. In a myopic eye, the image of the object is formed .........
(c) infront of the retina
3. If a Substance is heated or cooled, the change in mass of that substance is .........
(c) zero
4. Which of the following is a triatomic molecule?
(c) Carbondioxide
5. The process of coating the surface of Metal with a thin layer of zinc is called .........
(c) galvanization
6. Which of the following is the universal solvent
(c) water
7. Oxygen is produced at what point during photosynthesis?
(c) when H₂O is splitted
8. During transpiration there is loss of
(c) water
9. Identify the exocrine gland
(c) Salivary gland
10. Syngamy results in the formation of
(c) Zygote
11. The loss of one or more chromosome in a ploidy is called
(b) Aneuploidy
12. Vomiting centre is located in
(a) medulla oblongata
PART II - SOLUTIONS (7 × 2 = 14)
NOTE: (i) Answer any Seven questions. (ii) Question No: 22 is compulsory.
13. Differentiate mass and weight
Mass:
- It is the quantity of matter contained in a body.
- It is a scalar quantity.
- Its SI unit is kilogram (kg).
- It remains constant everywhere.
- It is the gravitational force exerted on a body due to Earth's gravity.
- It is a vector quantity.
- Its SI unit is newton (N).
- It varies from place to place.
14. State the law of volume
The law of volume (Charles's Law) states that when the pressure of a gas is kept constant, the volume of a gas is directly proportional to the absolute temperature of the gas. (V ∝ T)
15. Define the unit of current?
The SI unit of electric current is the Ampere (A). One Ampere is defined as the flow of one coulomb of charge through a conductor in one second. (1A = 1 C/s)
16. What is molar volume of gas?
The volume occupied by one mole of any gas at Standard Temperature and Pressure (STP) is called molar volume. At STP, the molar volume of any gas is 22.4 litres/mole or 22.4 dm³/mole.
17. Define the term solutions.
A solution is a homogeneous mixture of two or more substances. It consists of a solute (the substance being dissolved) and a solvent (the substance in which the solute dissolves).
18. What is photosynthesis? where in a cell does it occur?
Photosynthesis: It is the process by which green plants, algae, and some bacteria convert light energy into chemical energy. During photosynthesis, carbon dioxide and water are used to synthesize glucose (food), with oxygen being released as a byproduct.
Location: It occurs in the chloroplasts of plant cells.
Location: It occurs in the chloroplasts of plant cells.
19. What is bolting? How can it be induced artificially?
Bolting: It is the premature elongation of the internodes of a plant's stem just before flowering.
Artificial Induction: Bolting can be induced artificially by spraying the plants with Gibberellins.
Artificial Induction: Bolting can be induced artificially by spraying the plants with Gibberellins.
20. What are the structures involved in the protection of brain?
The brain is protected by:
- The Cranium (Skull): A bony box that encloses the brain.
- Cerebral Meninges: Three protective layers covering the brain - Dura mater (outer), Arachnoid mater (middle), and Pia mater (inner).
- Cerebrospinal Fluid (CSF): A fluid that fills the space between the meninges and acts as a shock absorber.
21. Draw the structure of Adrenal gland and label its parts?
A diagram of the Adrenal Gland should be drawn showing the outer adrenal cortex and the inner adrenal medulla, located on top of the kidney.
22. 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:
1/10 = 1/v - 1/(-20)
1/10 = 1/v + 1/20
1/v = 1/10 - 1/20
1/v = (2 - 1) / 20
1/v = 1/20
v = +20 cm
Image distance (v) = 20 cm.
Nature of the image: Since 'v' is positive, the image is real and inverted. It is formed at the same distance from the lens as the object (at 2F), so it is of the same size as the object.
- Object distance (u) = -20 cm
- Focal length (f) = +10 cm (convex lens)
1/10 = 1/v - 1/(-20)
1/10 = 1/v + 1/20
1/v = 1/10 - 1/20
1/v = (2 - 1) / 20
1/v = 1/20
v = +20 cm
Image distance (v) = 20 cm.
Nature of the image: Since 'v' is positive, the image is real and inverted. It is formed at the same distance from the lens as the object (at 2F), so it is of the same size as the object.
PART III - SOLUTIONS (7 × 4 = 28)
NOTE: (i) Answer any Seven questions. (ii) Question No: 32 is compulsory.
23. (i) Differentiate convex lens and concave lens (ii) Why does the sky appear in blue colour?
(i) Differentiating Convex and Concave Lens:
(ii) Why the sky appears blue: The sky appears blue due to a phenomenon called Rayleigh scattering. When sunlight enters the Earth's atmosphere, the gases and particles in the air scatter the light in all directions. Blue light has a shorter wavelength and is scattered more effectively than other colors like red and yellow, which have longer wavelengths. This scattered blue light reaches our eyes from all parts of the sky, making it appear blue.
| Feature | Convex Lens | Concave Lens |
|---|---|---|
| Shape | Thicker at the center, thinner at the edges. | Thinner at the center, thicker at the edges. |
| Action on light | Converges parallel rays of light. | Diverges parallel rays of light. |
| Focus | Has a real focus. | Has a virtual focus. |
| Image formed | Forms real, inverted images and a virtual, erect image. | Forms only virtual, erect, and diminished images. |
(ii) Why the sky appears blue: The sky appears blue due to a phenomenon called Rayleigh scattering. When sunlight enters the Earth's atmosphere, the gases and particles in the air scatter the light in all directions. Blue light has a shorter wavelength and is scattered more effectively than other colors like red and yellow, which have longer wavelengths. This scattered blue light reaches our eyes from all parts of the sky, making it appear blue.
24. Derive ideal gas equation.
The ideal gas equation is derived by combining three gas laws:
V ∝ (1/P) × T × n
V ∝ nT/P
PV ∝ nT
To replace the proportionality sign with an equality sign, we introduce a constant 'R', known as the universal gas constant.
PV = nRT
This is the ideal gas equation.
- Boyle's Law: At constant temperature, the volume (V) of a gas is inversely proportional to its pressure (P).
V ∝ 1/P ---(1) - Charles's Law: At constant pressure, the volume (V) of a gas is directly proportional to its absolute temperature (T).
V ∝ T ---(2) - Avogadro's Law: At constant temperature and pressure, the volume (V) of a gas is directly proportional to the number of moles (n).
V ∝ n ---(3)
V ∝ (1/P) × T × n
V ∝ nT/P
PV ∝ nT
To replace the proportionality sign with an equality sign, we introduce a constant 'R', known as the universal gas constant.
PV = nRT
This is the ideal gas equation.
32. (i) What happens when MgSO₄. 7H₂O is heated?. Write the appropriate equations. (ii) A solution was prepared by dissolving 25g of sugar in 100 g of water. Calculate the mass percentage of solute?
(i) Heating of MgSO₄·7H₂O:
When Magnesium sulphate heptahydrate (Epsom salt) is heated, it loses its water of crystallization and becomes anhydrous magnesium sulphate, a white powder.
Equation:
MgSO₄·7H₂O(s) → (Heat) → MgSO₄(s) + 7H₂O(g)
(ii) Calculation of Mass Percentage:
Given:
Mass of solution = 25 g + 100 g = 125 g
Mass percentage of solute = (Mass of solute / Mass of solution) × 100
Mass percentage = (25 / 125) × 100
Mass percentage = (1 / 5) × 100
Mass percentage = 20%
When Magnesium sulphate heptahydrate (Epsom salt) is heated, it loses its water of crystallization and becomes anhydrous magnesium sulphate, a white powder.
Equation:
MgSO₄·7H₂O(s) → (Heat) → MgSO₄(s) + 7H₂O(g)
(ii) Calculation of Mass Percentage:
Given:
- Mass of solute (sugar) = 25 g
- Mass of solvent (water) = 100 g
Mass of solution = 25 g + 100 g = 125 g
Mass percentage of solute = (Mass of solute / Mass of solution) × 100
Mass percentage = (25 / 125) × 100
Mass percentage = (1 / 5) × 100
Mass percentage = 20%
PART IV - SOLUTIONS (3 × 7 = 21)
NOTE: (i) Answer all the questions. (ii) Draw diagram wherever necessary.
33. (a) Deduce the equation of a force using Newtons second law of motion.
According to Newton's second law of motion, the force (F) acting on a body is directly proportional to the rate of change of its linear 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', causing its final velocity to become 'v'.
F ∝ m(v - u) / t
We know that acceleration (a) = (v - u) / t.
So, F ∝ ma
Introducing a proportionality constant, k:
F = kma
The units of force, mass, and acceleration are chosen such that the value of k is 1.
Hence, F = ma. This is the equation for force.
Let a body of mass 'm' be moving with an initial velocity 'u'. Let a force 'F' act on it for a time 't', causing its final velocity to become 'v'.
- Initial momentum (p₁) = mu
- Final momentum (p₂) = mv
- Change in momentum (Δp) = p₂ - p₁ = mv - mu = m(v - u)
- Rate of change of momentum = Change in momentum / time = m(v - u) / t
F ∝ m(v - u) / t
We know that acceleration (a) = (v - u) / t.
So, F ∝ ma
Introducing a proportionality constant, k:
F = kma
The units of force, mass, and acceleration are chosen such that the value of k is 1.
Hence, F = ma. This is the equation for force.
OR
(b) (i) State Joule's law of heating (ii) An alloy of nickel and chromium is used as the heating element - why? (iii) How does a fuse wire protect electrical appliances?
(i) Joule's Law of Heating: It states that the heat (H) produced in a conductor is directly proportional to:
(ii) Why Nichrome is used as a heating element: An alloy of nickel and chromium (Nichrome) is used as a heating element because it has:
(iii) How a fuse wire protects appliances: A fuse wire is made of an alloy with a low melting point. It is connected in series with the electrical appliance. When an excessive current (due to short-circuiting or overloading) flows through the circuit, the fuse wire heats up rapidly (as per H = I²Rt). It melts and breaks the circuit, stopping the flow of current and thus protecting the expensive appliance from damage.
- the square of the current (I²) flowing through it,
- the resistance (R) of the conductor, and
- the time (t) for which the current flows.
(ii) Why Nichrome is used as a heating element: An alloy of nickel and chromium (Nichrome) is used as a heating element because it has:
- High Resistivity: It offers high resistance to the flow of current, thus producing a large amount of heat.
- High Melting Point: It can withstand very high temperatures without melting.
- Resistance to Oxidation: It does not easily oxidize (burn) even when red hot.
(iii) How a fuse wire protects appliances: A fuse wire is made of an alloy with a low melting point. It is connected in series with the electrical appliance. When an excessive current (due to short-circuiting or overloading) flows through the circuit, the fuse wire heats up rapidly (as per H = I²Rt). It melts and breaks the circuit, stopping the flow of current and thus protecting the expensive appliance from damage.
35. (a) (i) What is transpiration?. Give the importance of transpiration (ii) What are synthetic auxins? Give examples. (iii) Which hormone induces parthenocarpy in tomatoes?
(i) Transpiration and its Importance:
- Transpiration: It is the biological process of loss of water in the form of water vapour from the aerial parts of the plant, mainly through the stomata in the leaves.
- Importance of Transpiration:
- It creates a 'transpiration pull' which is responsible for the upward movement of water from the roots.
- It helps in the absorption and transport of minerals from the soil.
- It helps in maintaining the temperature of the plant by providing a cooling effect.
- These are man-made chemicals that mimic the function of natural auxins in plants. They are widely used in agriculture and horticulture.
- Examples: 2,4-D (2,4-Dichlorophenoxyacetic acid) and NAA (Naphthalene Acetic Acid).
- Auxins are the primary hormones that induce parthenocarpy (development of fruit without fertilization) in tomatoes, leading to the production of seedless tomatoes. Gibberellins can also induce this effect.
OR
(b) How is the structure of DNA organised? What is the biological significance of DNA?
Structure of DNA (Watson and Crick Model):
- DNA is a double-stranded helix, resembling a twisted ladder.
- Each strand is a polynucleotide, made up of repeating units called nucleotides.
- A nucleotide consists of three components: a deoxyribose sugar, a phosphate group, and a nitrogenous base.
- The 'backbone' of each strand is made of alternating sugar and phosphate groups.
- There are four nitrogenous bases: Adenine (A), Guanine (G), Cytosine (C), and Thymine (T).
- The two strands are held together by hydrogen bonds between the bases. Adenine always pairs with Thymine (A-T) via two hydrogen bonds, and Guanine always pairs with Cytosine (G-C) via three hydrogen bonds. This is called complementary base pairing.
- The two strands run in opposite directions, a property called anti-parallel orientation.
- Hereditary Material: DNA is the genetic material that carries the instructions for the development, functioning, growth, and reproduction of all known organisms and many viruses.
- Control of Metabolism: It controls all the metabolic activities of the cell by directing the synthesis of proteins and enzymes.
- Replication: DNA has the unique ability to replicate itself, ensuring that genetic information is passed on accurately from one generation to the next.
- Variation: It is responsible for the variations that occur through mutation and recombination, which are the basis of evolution.
Original Question Paper
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