10th Science Quarterly Exam 2024 - Original Question Paper with Answer Key | Tiruppur District

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

10th Science Quarterly Exam 2024 Question Paper

PART I

NOTE: Answer all the questions. Choose the most appropriate answer from the given four alternatives and write the option code and the corresponding Answer. (12×1=12)

1. Newton's III law is applicable

2. In a myopic eye, the image of the object is formed

3. If a Substance is heated or cooled, the change in mass of that substance is

4. Which of the following is a triatomic molecule?

5. The process of coating the surface of Metal with a thin layer of zinc is called

6. Which of the following is the universal solvent

7. Oxygen is produced at what point during photosynthesis?

8. During transpiration there is loss of

9. Identify the exocrine gland

10. Syngamy results in the formation of

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

NOTE: Answer any Seven questions. Question No: 22 is compulsory. (7×2=14)

13. Differentiate mass and weight

Mass	Weight
It is the quantity of matter contained in a body.	It is the gravitational force exerted on a body due to gravity.
It is a scalar quantity.	It is a vector quantity.
Its SI unit is kilogram (kg).	Its SI unit is newton (N).
It remains constant everywhere.	It varies from place to place.

14. State the law of volume

Gay-Lussac's Law (Law of Volume): 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 (1 A = 1 C/s).

16. What is molar volume of gas?

Molar volume is the volume occupied by one mole of any gas at Standard Temperature and Pressure (STP). At STP (0°C or 273.15 K and 1 atm pressure), the molar volume of an ideal gas is approximately 22.4 litres/mol.

17. Define the term solutions.

A solution is a homogeneous mixture of two or more substances. The component present in a lesser amount is called the solute, and the component present in a larger amount is called the solvent.

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), and oxygen is released as a byproduct.

Location: Photosynthesis occurs in the chloroplasts within the plant cells, specifically in the mesophyll cells of leaves.

19. What is bolting? How can it be induced artificially?

Bolting: It is the premature elongation of the internodes of a plant stem just before flowering. This leads to early flower and seed production in biennial or rosette plants.

Artificial Induction: Bolting can be induced artificially by the application of gibberellins.

20. What are the structures involved in the protection of brain?

The brain is protected by three main structures:

The Cranium (Skull): A bony case that encloses the brain.
The Meninges: Three protective layers of tissue (dura mater, arachnoid mater, pia mater) that cover the brain and spinal cord.
Cerebrospinal Fluid (CSF): A clear fluid that circulates around the brain and spinal cord, acting as a shock absorber.

21. Draw the structure of Adrenal gland and label its parts?

The adrenal gland consists of two main parts:

Adrenal Cortex: The outer region that produces steroid hormones.
Adrenal Medulla: The inner region that produces catecholamines (adrenaline and noradrenaline).

22. (Compulsory) 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 sign convention)
Focal length (f) = +10 cm (for a convex lens)

Using the lens formula: 1/f = 1/v - 1/u

1/10 = 1/v - 1/(-20)

1/10 = 1/v + 1/20

1/v = 1/10 - 1/20

1/v = (2 - 1) / 20 = 1/20

v = +20 cm

Nature of the image:

Since 'v' is positive, the image is real.
Magnification (m) = v/u = 20 / -20 = -1. Since magnification is negative, the image is inverted.
Since the magnitude of magnification is 1, the image is of the same size as the object.

Conclusion: The image is formed at 20 cm on the opposite side of the lens. It is real, inverted, and of the same size as the object.

PART III

NOTE: Answer any Seven question. Question No; 32 is compulsory. (7×4=28)

23. (i) Differentiate convex lens and concave lens (ii) Why does the sky appear in blue colour?

(i) Differentiation between Convex and Concave Lens:

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.
Focal Length	Positive	Negative
Image Formed	Forms real and inverted images (mostly), and one case of virtual and erect image.	Forms only virtual, erect, and diminished images.

(ii) Why the sky appears blue:

The blue color of the sky is due to a phenomenon called Rayleigh scattering. When sunlight enters the Earth's atmosphere, it interacts with the gas molecules (like nitrogen and oxygen) which are much smaller than the wavelength of visible light. These molecules scatter the shorter wavelengths (blue and violet) more effectively than the longer wavelengths (red, orange). Since our eyes are more sensitive to blue light than violet, we perceive the sky as blue.

24. Derive ideal gas equation.

The ideal gas equation is derived by combining three fundamental gas laws:

Boyle's Law: At constant temperature (T) and number of moles (n), the volume (V) of a gas is inversely proportional to its pressure (P).
V ∝ 1/P .....(1)
Charles's Law: At constant pressure (P) and number of moles (n), the volume (V) of a gas is directly proportional to its absolute temperature (T).
V ∝ T .....(2)
Avogadro's Law: At constant temperature (T) and pressure (P), the volume (V) of a gas is directly proportional to the number of moles (n).
V ∝ n .....(3)

By combining equations (1), (2), and (3), we get:
V ∝ (1/P) × T × n
V ∝ nT/P
V = R (nT/P) (where R is the proportionality constant called the Universal Gas Constant)

Rearranging the equation, we get the ideal gas equation:
PV = nRT

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 (Epsom Salt):

When Magnesium Sulphate Heptahydrate (MgSO₄·7H₂O) is heated, it loses its water of crystallization to form anhydrous magnesium sulphate. This process is called dehydration.

Equation:

MgSO₄·7H₂O(s) → (Heat) → MgSO₄(s) + 7H₂O(g)

(Magnesium Sulphate Heptahydrate) → (Anhydrous Magnesium Sulphate) + (Water Vapour)

(ii) Calculation of Mass Percentage of Solute:

Given:

Mass of solute (sugar) = 25 g
Mass of solvent (water) = 100 g

Step 1: Calculate the mass of the solution.

Mass of solution = Mass of solute + Mass of solvent

Mass of solution = 25 g + 100 g = 125 g

Step 2: Calculate the mass percentage of the solute.

Mass % of solute = (Mass of solute / Mass of solution) × 100

Mass % of solute = (25 / 125) × 100

Mass % of solute = (1/5) × 100 = 20%

The mass percentage of sugar in the solution is 20%.

PART IV

NOTE: Answer all the questions. Draw diagram wherever necessary. (3x7=21)

33. (a) Deduce the equation of a force using Newtons second law of motion.

Newton's Second Law of Motion: It states that "the rate of change of momentum of a body is directly proportional to the applied unbalanced force and takes place in the direction of the force."

Let an object of mass 'm' be moving with an initial velocity 'u'. A force 'F' is applied on it for a time 't', which changes its velocity to 'v'.

Initial Momentum (p₁): The initial momentum of the body is given by:
p₁ = m × u
Final Momentum (p₂): The final momentum of the body is given by:
p₂ = m × v
Change in Momentum (Δp): The change in momentum is the final momentum minus the initial momentum.
Δp = p₂ - p₁ = mv - mu = m(v - u)
Rate of Change of Momentum: This is the change in momentum per unit time.
Rate of change of momentum = Δp / t = m(v - u) / t
Applying Newton's Second Law: According to the law, the applied force (F) is directly proportional to the rate of change of momentum.
F ∝ m(v - u) / t
Introducing Acceleration: We know that acceleration (a) is the rate of change of velocity, a = (v - u) / t. Substituting this into the equation:
F ∝ m × a
Final Equation: To convert the proportionality into an equation, we introduce a constant of proportionality, k.
F = k × m × a
The value of k is taken as 1 by choosing the units of force, mass, and acceleration appropriately (e.g., 1 Newton is the force that produces an acceleration of 1 m/s² in a mass of 1 kg).
Therefore, the equation for force is:
F = ma

35. (b) How is the structure of DNA organised? What is the biological significance of DNA?.

Structure of DNA (Watson and Crick Model):

The DNA molecule is a double helix, resembling a twisted ladder. Its structure is organized as follows:

Two Polynucleotide Strands: DNA consists of two long chains of nucleotides that are coiled around a central axis to form a right-handed double helix.
Sugar-Phosphate Backbone: The "sides" of the ladder are made of alternating sugar (deoxyribose) and phosphate groups. This backbone provides structural support to the molecule.
Nitrogenous Bases: The "rungs" of the ladder are formed by pairs of nitrogenous bases. There are four bases in DNA: Adenine (A), Guanine (G), Cytosine (C), and Thymine (T).
Complementary Base Pairing: The bases pair in a specific way due to their chemical structures: Adenine always pairs with Thymine (A-T) using two hydrogen bonds, and Guanine always pairs with Cytosine (G-C) using three hydrogen bonds. This is known as complementary base pairing.
Antiparallel Strands: The two strands of the DNA helix run in opposite directions. This orientation is called antiparallel. One strand runs in the 5' to 3' direction, while the other runs in the 3' to 5' direction.

Biological Significance of DNA:

DNA is fundamentally important for life due to its following roles:

Carrier of Genetic Information: DNA carries the complete set of genetic instructions required for the development, functioning, growth, and reproduction of all living organisms.
Heredity: It is the molecule of heredity, responsible for passing genetic traits from parents to offspring, ensuring the continuity of life.
Protein Synthesis: DNA contains the "code" or template for synthesizing all the proteins in an organism. Proteins perform a vast array of functions, acting as enzymes, structural components, and signaling molecules.
Replication: DNA has the unique ability to make exact copies of itself. This process, called replication, is crucial for cell division, growth, and repair, ensuring that each new cell receives a complete set of genetic information.
Source of Variation: Changes or mutations in the DNA sequence can lead to variations among individuals. This genetic variation is the raw material for natural selection and evolution.