10th Science Quarterly Exam 2024
Question Paper with Solutions
QUARTERLY COMMON EXAMINATION - 2024
Class: 10 - Std | Subject: SCIENCE
Time: 3.00 Hrs. | Marks: 75
PART - I (12 x 1 = 12)
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.
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 (7 x 2 = 14)
Note: Answer any seven questions. Question No.22 is compulsory.
13) State the principle of moments.
When a body is in equilibrium, the sum of clockwise moments about a point is equal to the sum of anticlockwise moments about the same point.
Sum of clockwise moments = Sum of anticlockwise moments
14) State Boyle's law.
Boyle's law states that when the temperature of a gas is kept constant, the volume of a given mass of gas is inversely proportional to its pressure.
V ∝ 1/P (at constant T and n)
15) Define Atomicity.
Atomicity is defined as the total number of atoms present in one molecule of an element, compound or a substance.
Examples:
- Oxygen (O₂) has an atomicity of 2.
- Ozone (O₃) has an atomicity of 3.
16) State two conditions necessary for rusting of iron.
The two conditions necessary for the rusting of iron are:
- 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: Sugar dissolved in water.
- iii) Solid in solid: Alloys like Brass (Zinc in Copper).
- iv) Gas in gas: Air (a mixture of gases like nitrogen, oxygen, etc.).
18) Write the dental formula of rabbit.
The dental formula of a rabbit is I 2/1, C 0/0, PM 3/2, M 3/3.
This represents the number of incisors (I), canines (C), premolars (PM), and molars (M) in one half of the upper and lower jaw. Rabbits have a total of 28 teeth.
19) What is bolting? How can it be induced artificially?
Bolting is the sudden elongation of the internodes of a plant just before flowering. This leads to premature flowering.
It can be induced artificially by the application of gibberellins, a plant growth hormone.
20) Identify the parts A, B, C and D
- A: Exine
- B: Intine
- C: Generative cell
- D: Vegetative nucleus
21) Who discovered Rh factor? Why was it named so?
Karl Landsteiner and Alexander Wiener discovered the Rh factor in 1940.
It was named the 'Rh factor' because it was first discovered in the blood of Rhesus monkeys.
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 seconds = 300 s
Formula:
According to Joule's law of heating, H = I²Rt
Calculation:
H = (6)² × 5 × 300
H = 36 × 5 × 300
H = 180 × 300
H = 54000 J or 54 kJ
The amount of heat produced is 54,000 Joules.
PART - III (7 x 4 = 28)
Note: Answer any seven questions. Question No.32 is compulsory.
23) Differentiate the eye defects: Myopia and Hypermetropia.
| Feature | Myopia (Near-sightedness) | Hypermetropia (Far-sightedness) |
|---|---|---|
| Definition | A person can see nearby objects clearly but cannot see distant objects distinctly. | A person can see distant objects clearly but cannot see nearby objects distinctly. |
| Cause | The eyeball is too long, or the focal length of the eye lens is too short. | The eyeball is too short, 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.
- 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)
Combining equations (1), (2), and (3), we get:
V ∝ nT/P
V = R (nT/P)
Rearranging the equation, we get:
PV = nRT
This is the ideal gas equation. Here, R is the universal gas constant (8.31 J mol⁻¹ K⁻¹).
25) Give the applications of universal law of gravitation.
- It helps in determining the dimensions (mass, radius) of the celestial bodies like the Sun, Earth, and Moon.
- It helps in predicting the orbits of the planets and their satellites.
- It explains the force (gravity) that binds us to the Earth.
- It is responsible for the motion of the Moon around the Earth and the Earth around the Sun.
- It helps in understanding the formation of tides in oceans and seas.
- It is used to predict the path of astronomical bodies and to launch artificial satellites and space probes.
26) Write notes on i) saturated solution ii) unsaturated solution.
A saturated solution is a solution in which no more solute can be dissolved in the solvent at a given temperature. If more solute is added, it will not dissolve and will remain as a separate phase.ii) Unsaturated Solution:
Example: Adding 36 g of NaCl to 100 g of water at 25°C creates a saturated solution. Any more salt added will not dissolve.
An unsaturated solution is a solution that contains less solute than the maximum amount that can be dissolved in the solvent at a given temperature. It has the capacity to dissolve more solute.
Example: Adding 10 g of NaCl to 100 g of water at 25°C creates an unsaturated solution, as more salt can still be dissolved.
27) In what way hygroscopic substances differ from deliquescent substances.
| Feature | Hygroscopic Substances | Deliquescent Substances |
|---|---|---|
| Action | They absorb moisture from the atmosphere. | They absorb enough moisture from the atmosphere to dissolve in it. |
| Physical State | They do not change their physical state on absorbing water. | They change their physical state from solid to a liquid solution. |
| Nature | Can be amorphous solids or liquids. | Are crystalline solids. |
| Example | Concentrated Sulphuric acid (H₂SO₄), Silica gel, Anhydrous Copper Sulphate. | Sodium hydroxide (NaOH), Calcium chloride (CaCl₂), Ferric chloride (FeCl₃). |
28) Where are estrogens produced? What is the role of estrogens in the human body?
Production: Estrogens are primarily produced by the Graafian follicles in the ovaries of females.
Role of Estrogens:
- Puberty: Initiates the physical changes that occur during puberty in females.
- Secondary Sexual Characteristics: Responsible for the development of female secondary sexual characteristics, such as the growth of breasts, widening of the pelvis, and growth of pubic and axillary hair.
- Menstrual Cycle: It helps in the maturation of ovarian follicles and regulates the uterine changes during the menstrual cycle.
- Ovum Maturation: It controls the maturation and release of the ovum (egg).
29) Write the physiological effects of gibberellins.
- Stem Elongation: They cause an extraordinary elongation of the stem, especially in genetically dwarf plants.
- Bolting: They induce bolting (sudden internode elongation followed by flowering) in rosette plants like cabbage and beet.
- Seed Germination: They break the dormancy of seeds, buds, and tubers, promoting germination.
- Parthenocarpy: They can induce the development of seedless fruits (parthenocarpy), particularly in grapes and tomatoes.
- Flowering: They promote flowering in long-day plants.
30) Enumerate the functions of blood.
- Transport:
- Transports respiratory gases like oxygen (from lungs to tissues) and carbon dioxide (from tissues to lungs).
- 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 to the excretory organs.
- Regulation:
- Regulates body temperature by distributing heat.
- Maintains the pH of the body by means of buffers.
- Regulates the water balance in the body.
- Protection:
- Protects the body from disease-causing germs through white blood cells (leucocytes).
- Helps in blood clotting to prevent excessive blood loss at the site of an injury.
31) (i) Match the following (ii) Fill in the blanks
(i) Match the following:
- A. Nissil'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 = 100 g/mol
Step 2: Calculate the percentage composition of each element
% of Calcium (Ca) = (Mass of Ca / Molar mass of CaCO₃) × 100
% of Ca = (40 / 100) × 100 = 40%
% of Carbon (C) = (Mass of C / Molar mass of CaCO₃) × 100
% of C = (12 / 100) × 100 = 12%
% of Oxygen (O) = (Mass of 3 Oxygen atoms / Molar mass of CaCO₃) × 100
% of O = (48 / 100) × 100 = 48%
PART - IV (3 x 7 = 21)
Note: Answer all the questions. Draw diagrams wherever necessary.
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?
(OR)
(b) (i) State and prove the law of conservation of linear momentum. (ii) Why does the sky appear in blue colour?
(a) Electric Current and its Measurement
(i) Electric Current:
Electric current is defined as the rate of flow of electric charges (electrons) in a conductor.
Current (I) = Charge (Q) / Time (t)
(ii) Unit of Electric Current:
The SI unit of electric current is the Ampere (A).
Definition of Ampere: One Ampere is defined as the current that flows when one coulomb of charge passes through a cross-section of a conductor in one second.
(iii) Instrument and Connection:
The instrument used to measure electric current is an Ammeter.
An ammeter should always be connected in series in the circuit so that the total current of the circuit flows through it.
(b) Conservation of Momentum and Blue Sky
(i) Law of Conservation of Linear Momentum:
Statement: In the absence of any external force, the algebraic sum of the momenta of a system of colliding bodies remains constant.
Proof: Consider two bodies, A and B, of masses m₁ and m₂ moving with initial velocities u₁ and u₂ in a straight line. Let them collide for a time 't'. After the collision, their velocities become v₁ and v₂.By Newton's third law of motion, the force exerted by B on A is equal and opposite to the force exerted by A on B.
- Force exerted by A on B (F_B) = m₂(v₂ - u₂)/t
- Force exerted by B on A (F_A) = m₁(v₁ - u₁)/t
F_A = -F_B
m₁(v₁ - u₁)/t = -[m₂(v₂ - u₂)/t]
m₁v₁ - m₁u₁ = -m₂v₂ + m₂u₂
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
Total momentum before collision = Total momentum after collision. Hence, the law is proved.
(ii) Why the sky appears blue:
The sky appears blue due to a phenomenon called Rayleigh scattering. When sunlight enters the Earth's atmosphere, it is scattered by the tiny gas molecules and dust particles present. According to Rayleigh's scattering law, the amount of scattering is inversely proportional to the fourth power of the wavelength of light (Scattering ∝ 1/λ⁴). Since blue light has a shorter wavelength than red light, it is scattered much more effectively in all directions by the atmospheric particles. When we look at the sky, this scattered blue light reaches our eyes, 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.
(OR)
(b) (i) What happens when MgSO₄.7H₂O is heated? Write the appropriate equation. (ii) Define solubility. (iii) Define Hydrated salt.
(a) RMM, Vapour Density and Amalgam
(i) Relationship between Relative Molecular Mass (RMM) and Vapour Density (VD):
Vapour Density (VD) is the ratio of the mass of a certain volume of a gas or vapour to the mass of the same volume of hydrogen at the same temperature and pressure.
VD = (Mass of a given volume of gas) / (Mass of the same volume of H₂)
By Avogadro's law, equal volumes of all gases under the same conditions contain an equal number of molecules. So, we can replace 'volume' with 'n molecules'.
VD = (Mass of 'n' molecules of gas) / (Mass of 'n' molecules of H₂)
VD = (Mass of 1 molecule of gas) / (Mass of 1 molecule of H₂)
VD = (Molecular mass of gas) / (Molecular mass of H₂)
Since the molecular mass of hydrogen (H₂) is 2,
VD = (Molecular mass of gas) / 2
Molecular mass = 2 × Vapour Density
Relative Molecular Mass = 2 × Vapour Density
(ii) Amalgam:
An amalgam is an alloy of mercury with one or more other metals.
Example: Dental amalgam, which is an alloy of mercury, silver, tin, and copper, used for filling dental cavities. Another example is Sodium amalgam (Na-Hg).
(b) Heating Epsom Salt, Solubility and Hydrated Salt
(i) Heating MgSO₄.7H₂O:
When Magnesium sulphate heptahydrate (MgSO₄.7H₂O), also known as Epsom salt, is gently heated, it loses its seven molecules of water of crystallization and becomes anhydrous magnesium sulphate, which is a white powder.
Equation:
MgSO₄.7H₂O(s) → (Heat) → MgSO₄(s) + 7H₂O(g)
(Magnesium sulphate heptahydrate) → (Anhydrous magnesium sulphate) + (Water vapour)
(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 specified temperature.
(iii) Hydrated Salt:
A hydrated salt is a crystalline salt that contains a definite number of water molecules loosely bound within its crystal structure. These water molecules are known as the "water of crystallization".
Example: Copper(II) sulphate pentahydrate (CuSO₄.5H₂O).
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.
(OR)
(b) (i) With a neat labelled diagram explain the structure of a neuron. (ii) Define reflex arc.
(a) Sexual Reproduction in Flowering Plants
(i) Events in Sexual Reproduction:
The major events in the sexual reproduction of a flowering plant are:
- Pollination: Transfer of pollen from anther to stigma.
- Fertilization: Fusion of male and female gametes to form a zygote.
- Formation of Fruit and Seed: Post-fertilization changes where the ovule develops into a seed and the ovary develops into a fruit.
(ii) First Event - Pollination and its Types:
Pollination 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 (Xenogamy): The transfer of pollen grains from the anther of one flower to the stigma of a flower on a different plant of the same species. This requires external agents like wind, water, insects, or birds.
(iii) Advantages and Disadvantages of Pollination:
Self-Pollination:Cross-Pollination:
- Advantages: Preserves parental characters, high success rate as it does not depend on external agents.
- Disadvantages: No new varieties are produced, continued self-pollination can lead to weaker progeny (inbreeding depression).
- Advantages: Introduces genetic variation leading to new varieties, offspring are healthier and more vigorous.
- Disadvantages: Highly dependent on external agents, there is significant wastage of pollen grains, it is not always certain.
(b) Neuron and 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:
- Cyton (Cell Body or Soma): It is the main part of the neuron, containing a large central nucleus and cytoplasm with granular structures called Nissl's granules.
- Dendrites: These are short, branched processes that arise from the cyton. They receive nerve impulses from other neurons and transmit them towards the cyton.
- Axon: This is a single, long, cylindrical process that arises from the cyton. It conducts nerve impulses away from the cell body to other neurons or effector organs. The axon is covered by a protective sheath called the myelin sheath, which is interrupted at intervals by gaps called Nodes of Ranvier. The end of the axon branches into axon terminals, which end in synaptic knobs.
(ii) Reflex Arc:
A reflex arc is the neural pathway that mediates a reflex action. It is the path along which nerve impulses are carried from a receptor to an effector to produce an immediate, involuntary response to a stimulus.
The components of a typical reflex arc are:
- Receptor: Senses the stimulus.
- Sensory (Afferent) Neuron: Transmits the impulse from the receptor to the central nervous system (spinal cord).
- Interneuron (Association Neuron): Located in the spinal cord, it processes the information and relays the impulse to a motor neuron.
- Motor (Efferent) Neuron: Carries the impulse from the central nervous system to the effector.
- Effector: The muscle or gland that responds to the stimulus.