10th Science Quarterly Exam 2024 - Original Question Paper with Solutions
Examination: Quarterly Common Examination – 2024
Standard: 10th Std
Subject: Science
District: Karur
Marks: 75
Time: 3.00 Hrs.
Original Question Paper
PART-I: Solutions
Note: (i) Answer All the questions. (ii) Choose the most appropriate answer from the given four alternatives and write option code and the corresponding answer. (12 X 1 = 12)
1) Impulse is equals to ____
2) Power of a lens is -4D, then its focal length is:
3) In the Given diagram, the possible direction of heat energy transformation is:
4) Kilowatt hour is the unit of:
5) Identify the non-aqueous solution.
6) The gram molecular mass of oxygen molecule is ____
7) The process of coating the surface of the metal with a thin layer of zinc is called ____
8) The essential parts of a flower are ____
9) Which organ acts as both exocrine gland as well as endocrine gland?
10) Node of Ranvier is found in:
11) Root hairs are ____
12) Kreb's cycle takes place in ____
PART-II: Solutions
Note: Answer any seven questions. Question No.22 is compulsory. (7 X 2 = 14)
13) State the principle of moments.
14) State Boyle's law
P ∝ 1/V
15) Define Atomicity.
16) State two conditions necessary for rusting of iron.
- Presence of air (oxygen).
- Presence of water (moisture).
17) Give an example each i) gas in liquid ii) solid in liquid iii) solid in solid iv) gas in gas
- i) Gas in liquid: Carbon dioxide dissolved in water (soda water).
- ii) Solid in liquid: Sodium chloride (salt) dissolved in water.
- iii) Solid in solid: Copper dissolved in gold (alloys like brass).
- iv) Gas in gas: A mixture of Helium and Oxygen gases (air).
18) Write the dental formula of rabbit.
19) What is bolting? How can it be induced artificially?
20) Identify the parts A, B, C and D
- A - Cytoplasm
- B - Nucleus
- C - Cell membrane
- D - Mitochondrion
21) Who discovered Rh factor? Why was it named so?
22) An electric heater of resistance 5 Ω is connected to an electric source. If a current of 6 A flows through the heater, then find the amount of heat produced in 5 minutes. (Compulsory)
Given:
- Resistance (R) = 5 Ω
- Current (I) = 6 A
- Time (t) = 5 minutes = 5 × 60 = 300 seconds
According to Joule's law of heating, the amount of heat produced (H) is given by the formula:
H = I²Rt
H = (6)² × 5 × 300
H = 36 × 5 × 300
H = 180 × 300
H = 54000 J or 54 kJ
Therefore, the amount of heat produced is 54,000 Joules.
PART-III: Solutions
Note: Answer any seven questions. Question No.32 is compulsory. (7 X 4 = 28)
23) Differentiate the eye defects: Myopia and Hypermetropia.
| Feature | Myopia (Short-sightedness) | Hypermetropia (Long-sightedness) |
|---|---|---|
| Definition | The eye defect where a person can see nearby objects clearly but cannot see distant objects distinctly. | The eye defect where a person can see distant objects clearly but cannot see nearby objects distinctly. |
| Cause | The eyeball is elongated, or the focal length of the eye lens is too short. | The eyeball is shortened, or the focal length of the eye lens is too long. |
| Image Formation | The image of a distant object is formed in front of the retina. | The image of a nearby object is formed behind the retina. |
| Correction | Corrected by using a concave lens of appropriate power. | Corrected by using a convex lens of appropriate power. |
24) Derive the ideal gas equation.
The ideal gas equation is an equation of state for a hypothetical ideal gas. It is derived from the combination of three empirical 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' 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)
Combining these three laws (1), (2), and (3), we get:
V ∝ (1/P) × T × n
V ∝ nT/P
By rearranging the terms, we get:
PV ∝ nT
This proportionality can be converted into an equation by introducing a constant, R, known as the universal gas constant.
PV = nRT
This equation is known as the Ideal Gas Equation. The value of R is 8.31 J mol⁻¹ K⁻¹.
25) Give the applications of universal law of gravitation.
- It helps in understanding the force that binds us to the Earth.
- It is used to determine the masses of the Earth, the Sun, the moon, and other celestial bodies.
- It explains the motion of the moon around the Earth and the motion of planets around the Sun.
- It helps in predicting the paths of astronomical bodies and the launching of artificial satellites.
- It helps in explaining the occurrence of tides in the oceans.
26) Write notes on i) saturated solution ii) unsaturated solution
i) Saturated Solution:
A saturated solution is a solution that contains the maximum amount of solute that can be dissolved in a given amount of solvent at a specific temperature. If more solute is added to a saturated solution, it will not dissolve and will settle at the bottom. The solution is in a state of dynamic equilibrium, where the rate of dissolution of the solute is equal to the rate of its precipitation.
ii) Unsaturated Solution:
An unsaturated solution is a solution that contains less solute than the maximum amount that can be dissolved in a given amount of solvent at a specific temperature. It has the capacity to dissolve more solute when added. Most solutions we encounter in daily life are unsaturated.
27) In what way hygroscopic substances differ from deliquescent substances.
| Feature | Hygroscopic Substances | Deliquescent Substances |
|---|---|---|
| Moisture Absorption | They absorb moisture from the atmosphere without changing their physical state. | They absorb enough moisture from the atmosphere to dissolve completely and form a solution. |
| Physical State | Does not change its state (e.g., a solid remains solid). | Changes from solid to a liquid or aqueous solution. |
| Extent of Absorption | Absorbs a limited amount of moisture. | Absorbs a large amount of moisture until fully dissolved. |
| Example | Concentrated Sulphuric acid (H₂SO₄), Quicklime (CaO), Silica gel. | Calcium chloride (CaCl₂), Sodium hydroxide (NaOH), Ferric chloride (FeCl₃). |
28) Where are estrogens produced? What is the role of estrogens in the human body?
Production: Estrogens are steroid hormones primarily produced by the Graafian follicles of the ovaries in females. Small amounts are also produced by the adrenal cortex and testes.
Role of Estrogens:
- They are responsible for the development of female secondary sexual characteristics during puberty, such as the growth of breasts, widening of the pelvis, and growth of pubic and axillary hair.
- They initiate the process of oogenesis (formation of ova).
- They stimulate the maturation of ovarian follicles in the ovary.
- They control the menstrual cycle by causing the proliferation of the uterine endometrium during the follicular phase.
29) Write the physiological effects of gibberellins.
The physiological effects of gibberellins are:
- Stem Elongation: They cause an extraordinary elongation of the stem, especially in genetically dwarf plants and rosette plants (bolting).
- Breaking Dormancy: They are effective in breaking the dormancy of buds and seeds.
- Parthenocarpy: Gibberellins can induce the development of seedless fruits (parthenocarpy), such as seedless tomatoes and grapes.
- Germination: They promote the germination of seeds by inducing the synthesis of hydrolytic enzymes like amylase.
30) Enumerate the functions of blood.
The main functions of blood can be categorized as follows:
- Transport:
- Transports respiratory gases (Oxygen and Carbon dioxide).
- Transports digested food materials (nutrients) to different body cells.
- Transports hormones from endocrine glands to their target organs.
- Transports nitrogenous waste products like ammonia, urea, and uric acid.
- Regulation:
- Regulates body temperature.
- Maintains the body's pH through its buffer systems.
- Regulates the water balance in the body.
- Protection:
- Plays a crucial role in the immune system by defending the body against pathogens (WBCs and antibodies).
- Prevents excessive blood loss through the process of clotting (platelets and clotting factors).
31) (i) Match the following (ii) Fill in the blanks
(i) Match the following:
- A. Nissl's granules - Cyton
- B. Hypothalamus - Forebrain
- C. Cerebellum - Hindbrain
- D. Schwann cell - Peripheral Nervous system
(ii) Fill in the blanks:
(a) The source of O₂ liberated in photosynthesis is water (H₂O).
(b) Mitochondria is ATP factory of the cells.
32) Calculate the % of each element in calcium carbonate. (Atomic mass: C-12, O-16, Ca-40) (Compulsory)
The chemical formula for calcium carbonate is CaCO₃.
Step 1: Calculate the molar mass of CaCO₃.
Molar Mass = (Atomic mass of Ca) + (Atomic mass of C) + 3 × (Atomic mass of O)
Molar Mass = 40 + 12 + 3 × 16
Molar Mass = 40 + 12 + 48
Molar Mass = 100 g/mol
Step 2: Calculate the percentage of each element.
Percentage of an element = (Mass of the element in the compound / Molar mass of the compound) × 100
Percentage of Calcium (Ca):
% Ca = (40 / 100) × 100 = 40%
Percentage of Carbon (C):
% C = (12 / 100) × 100 = 12%
Percentage of Oxygen (O):
% O = (48 / 100) × 100 = 48%
Thus, calcium carbonate contains 40% Calcium, 12% Carbon, and 48% Oxygen by mass.
PART-IV: Solutions
Note: Answer all the questions. Draw diagrams wherever necessary. (3 X 7 = 21)
33) (a) (i) What is meant by electric current? (ii) Name and define its unit. (iii) Which instrument is used to measure the electric current? How should it be connected in a circuit?
(i) Electric Current:
Electric current is defined as the rate of flow of electric charges (electrons) through a conductor. It is denoted by the symbol 'I'. The direction of conventional current is taken as the direction of flow of positive charges.
I = Q / t, where Q is the charge and t is the time.
(ii) Unit of Electric Current:
The SI unit of electric current is the Ampere (A).
Definition of one Ampere: One Ampere is defined as the current that flows through a conductor when a charge of one Coulomb passes any cross-section of the conductor in one second.
1 Ampere = 1 Coulomb / 1 second
(iii) Instrument and Connection:
The instrument used to measure electric current is the Ammeter.
An ammeter must always be connected in series with the component through which the current is to be measured. This is because the entire current of the circuit must pass through the ammeter for it to be measured correctly. An ideal ammeter has very low resistance.
(b) (i) State and prove the law of conservation of linear momentum. (ii) Why does the sky appear in blue colour?
(i) Law of Conservation of Linear Momentum:
Statement: In the absence of any external unbalanced force, the total linear momentum of a system of interacting objects remains constant.
Proof:
Consider two bodies, A and B, with masses m₁ and m₂ moving in the same direction along a straight line with initial velocities u₁ and u₂ respectively (where u₁ > u₂).
They collide for a short time 't' and then separate with final velocities v₁ and v₂.
Initial momentum of body A = m₁u₁
Initial momentum of body B = m₂u₂
Total initial momentum = m₁u₁ + m₂u₂
Final momentum of body A = m₁v₁
Final momentum of body B = m₂v₂
Total final momentum = m₁v₁ + m₂v₂
During collision, the force exerted by A on B (Fₐ) is Fₐ = m₂(v₂ - u₂)/t.
The force exerted by B on A (Fₙ) is Fₙ = m₁(v₁ - u₁)/t.
According to Newton's third law of motion, the force of action is equal and opposite to the force of reaction.
Fₐ = - Fₙ
m₂(v₂ - u₂)/t = - m₁(v₁ - u₁)/t
m₂(v₂ - u₂) = - m₁(v₁ - u₁)
m₂v₂ - m₂u₂ = -m₁v₁ + m₁u₁
Rearranging the terms:
m₁v₁ + m₂v₂ = m₁u₁ + m₂u₂
Total final momentum = Total initial momentum. This proves the law of conservation of linear momentum.
(ii) Why does the sky appear in blue colour?
The appearance of the blue colour of the sky is due to a phenomenon called Rayleigh scattering. Here's how it works:
- The sunlight entering the Earth's atmosphere consists of a spectrum of colours (VIBGYOR).
- The atmosphere is composed of tiny particles of gases (like nitrogen and oxygen) and dust, which are smaller than the wavelength of visible light.
- 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 light) are scattered much more effectively than longer wavelengths (like red and orange light).
- When sunlight passes through the atmosphere, the blue light is scattered in all directions by the air molecules. Our eyes perceive this scattered blue light coming from all parts of the sky, making the sky appear blue.
34) (a) (i) Derive the relationship between Relative molecular mass and Vapour density. (ii) What is meant by Amalgam? Give an example for it.
(i) Relationship between Relative Molecular Mass and Vapour Density:
Vapour Density (V.D.): It is defined as the ratio of the mass of a certain volume of a gas or vapour to the mass of the same volume of hydrogen gas, measured under the same conditions of temperature and pressure.
V.D. = (Mass of a given volume of gas or vapour at STP) / (Mass of the same volume of H₂ at STP) ... (1)
Relative Molecular Mass (R.M.M.): It is the ratio of the mass of one molecule of a substance to 1/12th the mass of one atom of Carbon-12.
According to Avogadro's hypothesis, equal volumes of all gases under the same conditions of temperature and pressure contain the same number of molecules. Let 'n' be the number of molecules in the given volume.
From equation (1):
V.D. = (Mass of 'n' molecules of the gas) / (Mass of 'n' molecules of H₂)
V.D. = (Mass of 1 molecule of the gas) / (Mass of 1 molecule of H₂)
Since a molecule of hydrogen is diatomic (H₂), its mass is 2 × (mass of one hydrogen atom) ≈ 2 × 1 = 2 amu.
V.D. = (Mass of 1 molecule of the gas) / 2
The mass of 1 molecule of the gas is its molecular mass.
V.D. = Molecular Mass / 2
Therefore, Molecular Mass = 2 × Vapour Density.
(ii) Amalgam:
An amalgam is an alloy in which one of the constituent metals is mercury. Depending on the proportion of mercury, it can be a liquid, a paste, or a solid.
Example: Dental amalgam, which is an alloy of mercury with silver, tin, copper, and zinc. It is used for filling dental cavities.
(b) (i) What happens when MgSO₄.7H₂O is heated? Write the appropriate equation. (ii) Define solubility. (iii) Define Hydrated salt.
(i) Heating of MgSO₄.7H₂O:
Magnesium sulphate heptahydrate (MgSO₄.7H₂O), also known as Epsom salt, is a crystalline hydrated salt. When it is heated, it loses its seven molecules of water of crystallization and becomes anhydrous magnesium sulphate (MgSO₄), which is a white amorphous powder. This phenomenon is called efflorescence.
Equation:
MgSO₄.7H₂O (s) → (on heating) → MgSO₄ (s) + 7H₂O (g)
(Magnesium sulphate heptahydrate) (Anhydrous magnesium sulphate)
(ii) Solubility:
Solubility is defined as the maximum mass of a solute (in grams) that can be dissolved in 100 grams of a solvent to form a saturated solution at a specific temperature and pressure.
Solubility = (Mass of solute / Mass of solvent) × 100
(iii) Hydrated Salt:
A hydrated salt is a crystalline salt molecule that is loosely attached to a definite number of water molecules. These water molecules are known as "water of crystallization". These salts lose their water of crystallization upon heating. For example, Copper (II) sulphate pentahydrate (CuSO₄.5H₂O) is a blue crystalline solid.
35) (a) (i) Write the events involved in the sexual reproduction of a flowering plant. (ii) Discuss the first event and write the types. (iii) Mention the advantages and the disadvantages of that event.
(i) Events in Sexual Reproduction of a Flowering Plant:
The major events involved are:
- Pollination: The transfer of pollen grains from the anther to the stigma of a flower.
- Fertilization: The fusion of the male gamete with the female gamete (egg) to form a zygote. In flowering plants, this involves double fertilization.
- Formation of Seed and Fruit: After fertilization, the ovule develops into a seed, and the ovary develops into a fruit.
(ii) Discussion of the First Event (Pollination) and its Types:
Pollination is the essential first step that brings the male and female gametophytes together. It is the process of transferring pollen grains from the anther (male part) to the stigma (female part) of a flower.
There are two main types of pollination:
- Self-Pollination (Autogamy): The transfer of pollen grains from the anther to the stigma of the same flower or another flower on the same plant.
- Cross-Pollination (Allogamy): The transfer of pollen grains from the anther of a flower on one plant to the stigma of a flower on another plant of the same species. This requires external agents like wind, water, insects, or birds.
(iii) Advantages and Disadvantages:
Self-Pollination:
- Advantages: It is almost certain in bisexual flowers. Parental characters are preserved. The plant does not need to produce large quantities of pollen.
- Disadvantages: It does not produce new varieties. Continuous self-pollination can lead to weaker progeny (inbreeding depression).
Cross-Pollination:
- Advantages: It introduces genetic variations, leading to healthier and more vigorous offspring. New varieties with desirable characters can be produced.
- Disadvantages: It is not always certain as it depends on external agents. The plant has to produce a large amount of pollen, which is wasteful. It may introduce some undesirable characters.
(b) (i) With a neat labelled diagram explain the structure of a neuron. (ii) Define reflex arc.
(i) Structure of a Neuron:
A neuron (or nerve cell) is the structural and functional unit of the nervous system. It consists of three main parts: the cyton (cell body), dendrites, and an axon.
[A neat, labelled diagram of a neuron should be drawn here, showing Cyton, Nucleus, Nissl's granules, Dendrites, Axon, Myelin Sheath, Node of Ranvier, and Axon terminal.]
- Cyton (Cell Body): This is the main part of the neuron, containing a large central nucleus and cytoplasm. The cytoplasm contains characteristic basophilic granules called Nissl's granules. The cyton is the site of metabolic activity.
- Dendrites: These are short, branched cytoplasmic extensions that arise from the cyton. They receive nerve impulses from other neurons and transmit them towards the cyton.
- Axon: This is a single, long, slender projection that arises from the cyton. It conducts nerve impulses away from the cell body to other neurons or to effector organs (muscles or glands). The axon is covered by a protective sheath called the myelin sheath, which is interrupted at intervals by gaps called Nodes of Ranvier. The myelin sheath helps in the rapid transmission of nerve impulses. The axon ends in branched terminals called axon terminals.
(ii) Define Reflex Arc:
A reflex arc is the neural pathway that mediates a reflex action. It includes a sensory receptor, a sensory (afferent) neuron, an interneuron (in the spinal cord), a motor (efferent) neuron, and an effector organ (like a muscle or gland). It allows for rapid, involuntary responses to stimuli without the immediate involvement of the brain.
