Brain Grain · braingrain.in
Science — Practice Paper · Set 1
Class: 7Samacheer KalviMax Marks: 59
Name: ____________________Reg No: ____________
Part I — Multiple Choice Questions 10 × 1 = 10
Choose the correct answer. (Answer all questions.)
1.A particle is moving in a circular path of radius r. The displacement after half a circle would beA. ZeroB. RC. 2rD. r/2[1]
2.Which of the following is a derived unit?A. massB. timeC. areaD. length[1]
3._______ is not a chemical change.A. Dissolution of ammonia in waterB. Dissolution of carbon-dioxide in waterC. Dissolution of oxygen in waterD. Melting of polar ice caps[1]
4.the outer most layer of an animal cell. Who am I?A. Cell wallB. NucleusC. Cell membraneD. Nuclear membrane[1]
5.Vegetative propagation by leaves takes place inA. BryophyllumB. FungiC. VirusD. Bacteria[1]
6.Give example forA. CormB. Tuber[1]
7.__________ is positively charged.A. ProtonB. ElectronC. MoleculeD. Neutron[1]
8.What is one way you might increase the stability of an object?A. lower the centre of gravityB. raise the centre of gravityC. increase the height of the objectD. shorten the base of the object[1]
9.Eggs are rich in __________A. ProteinB. CarbohydrateC. FatD. Acid[1]
10._________ of the following are endothermic changes.A. Condensation and meltingB. Condensation and freezingC. Evaporation and meltingD. Evaporation and freezing[1]
Part II — Fill in the Blanks 5 × 1 = 5
Fill in the blanks. (Answer all questions.)
11.Tuberculosis : air:: Cholera: _________[1]
12.___________ and ___________ planets never appear in the mid-night sky.[1]
13.Milli ampere: micro ampere: 10 -3 A : : _________[1]
14.length of scale : metre : : speed of aeroplane : _______[1]
15.Water : pipe : : Electric current: ______.[1]
Part III — True or False 5 × 1 = 5
Write True or False. (Answer all questions.)
16.NaCl represents one molecule of sodium chloride.[1]
17.Water is denser than kerosene.[1]
18.Ginger is an underground root.[1]
19.Animal cells have a cell wall.[1]
20.The electrons are positively charged.[1]
Part IV — Short Answer Questions 12 × 2 = 24
Answer briefly. (Answer all questions.)
21.Draw the diagram of a clinical thermometer and label its parts[2]
22.What are the three types of materials based on the absorption of light?[2]
23.Observe the picture and list down the changes that are accompanied in the picture.[2]
24.A B 1. Nylon Thermoplastic 2. PVC Thermosetting plastic 3. Bakelite Fibre 4. Teflon Wood pulp 5. Rayon Non-stick cookwares[2]
25.Write the items given here in the correct column (Stars, brick walls, plants, mirror, planets, electric light bulb, candle) Sources of Light Objects that reflect light[2]
26.Give two examples of thermosetting plastics.[2]
27.I am so exhausted. I am going to faint. What first aid will you give me to wake up?[2]
28.The distance of a person is 30 km and his displacement is 0 km. What do you infer from this?[2]
29.Define fuse.[2]
30.Give the expansions of PSLV and GSLV.[2]
31.Write notes on phyllode.[2]
32.What is the change in the surface of water?[2]
Part V — Long Answer Questions 3 × 5 = 15
Answer in detail. (Answer all questions.)
33.Do you remember the lesson studied in previous class, how will you find whether an object is living or non – living? Write it down. An object is living or non-living?[5]
34.Correct your friend who says “The acceleration gives the idea of how fast the position changes”.[5]
35.Why do antiseptics differ from disinfectants? Give one example of each.[5]
🔑 Show Answer Key — Set 1
- 1. (c) 2r
- 2. (c) area
- 3. (b) Melting of polar ice-caps II.Fill in the blanks : Filling up a balloon with hot air is a _______ change. Stretching gold coin into a ring is a _______ change. Opening a gas cylinder knob converts _______ fuel into _______ fuel. This is an example of _______ change. Spoiling of food is a _______ change. Respiration is a _______ change. physical physical liquid, gaseous, chemical chemical exothermic chemical
- 4. (c) Cell membrane
- 5. (a) Bryophyllum
- 6. Corm-e.g Colocasia Tuber – e.g Potato.
- 7. (a) Proton
- 8. (a) lower the centre of gravity
- 9. (a) Protein
- 10. (a) Condensation and melting
- 11. Water.
- 12. Mercury, Venus.
- 13. 10 -6 A
- 14. knot
- 15. wire
- 16. This statement is true. NaCl is the chemical formula that represents one molecule of sodium chloride, commonly known as table salt. The formula indicates that one molecule of sodium chloride is composed of one sodium atom (Na) and one chlorine atom (Cl) chemically bonded together in a fixed ratio. This 1:1 ratio is the simplest whole number ratio in which these elements combine to form the compound. The chemical formula NaCl tells us both the types of elements present and the exact number of atoms of each element in a single molecule of this ionic compound.
- 17. This statement is true. Water is denser than kerosene. Density is defined as the mass of a substance per unit volume. Water has a density of approximately 1 gram per cubic centimeter, while kerosene has a lower density of approximately 0.8 grams per cubic centimeter. Because water is denser than kerosene, if the two liquids are mixed together, kerosene will float on top of water and they will form separate layers due to their different densities.
- 18. False. The correct statement is that ginger is an underground stem, not a root. Ginger is a rhizome, which is a horizontal underground stem that grows beneath the soil surface. Although it appears root-like and is found underground, it has the characteristics of a stem, including nodes and internodes where buds can develop into new shoots. This is why ginger can be propagated by planting pieces of the rhizome, and new plants will grow from the buds present on these stem segments.
- 19. False. Animal cells do not have a cell wall. Only plant cells have a cell wall. The cell wall is a rigid outer layer found in plant cells that provides structural support, protection, and maintains the shape of the plant cell. Animal cells lack this cell wall and instead have only a cell membrane, which is a flexible, selectively permeable layer that controls the movement of substances in and out of the cell. This is one of the key differences between plant and animal cells.
- 20. False. The correct statement is: Electrons are negatively charged particles. Electrons are subatomic particles that orbit around the nucleus of an atom and carry a negative electrical charge. This negative charge is equal in magnitude but opposite in sign to the positive charge carried by protons in the nucleus. The charge of an electron is represented as -1 in terms of relative charge. This negative charge is a fundamental property of electrons and is essential for understanding atomic structure and chemical bonding.
- 21. (refer textbook)
- 22. The three types of materials based on the absorption and transmission of light are transparent materials, translucent materials, and opaque materials. Transparent materials allow light to pass through them completely, so objects on the other side can be seen clearly. Examples include clear glass, water, and air. Translucent materials allow some light to pass through but scatter it, so objects on the other side cannot be seen clearly. Examples include frosted glass, tracing paper, and thin cloth. Opaque materials do not allow light to pass through them at all, so objects on the other side cannot be seen. Examples include wood, metal, and brick.
- 23. The picture shows three types of changes. (a) Physical change: This refers to changes where only the physical properties of a substance are altered, such as changes in shape, size, state, or appearance, without any change in chemical composition. (b) Chemical change: This refers to changes where new substances are formed with different chemical properties and compositions, such as burning, rusting, or decomposition. (c) Exothermic: This refers to changes that release energy in the form of heat or light to the surroundings, making the surroundings warmer.
- 24. A B 1. Nylon Fibre 2. PVC Thermoplastic 3. Bakelite Thermosetting plastic 4. Teflon Non-stick cookwares 5. Rayon Wood pulp
- 25. Sources of Light: Stars, electric light bulb, candle, planets. Objects that reflect light: Brick walls, plants, mirror. Stars and planets are both sources of light, though stars produce their own light while planets reflect light from the sun. Electric light bulbs and candles are luminous objects that produce light. Brick walls, plants, and mirrors are non-luminous objects that reflect light falling on them. Mirrors reflect light regularly, while brick walls and plants reflect light diffusely.
- 26. Bakelite, Melamine.
- 27. If someone is exhausted and about to faint, the appropriate first aid is to help them rest and recover their energy. You should make them lie down in a comfortable position with their legs elevated to improve blood circulation to the brain. Provide them with water to drink to help them rehydrate. Loosen any tight clothing that might restrict breathing. Ensure they are in a cool, well-ventilated area. Allow them to rest for some time until they feel better. If the person loses consciousness or does not recover after resting, seek medical help immediately.
- 28. If the distance traveled by a person is 30 km and their displacement is 0 km, it means the person has returned to their starting point after covering a total path length of 30 km. Displacement is the shortest distance between the initial and final positions, and it is zero only when the initial and final positions are the same. This scenario implies a round trip or a journey that ends exactly where it began.
- 29. An electric fuse is a safety device which is used in household wiring and in many appliances to protect electrical circuits from damage caused by excessive current. It consists of a wire made of a material with a low melting point. When the current flowing through the circuit exceeds the rated capacity of the fuse, the wire becomes very hot and melts, breaking the circuit and stopping the flow of electricity. This prevents damage to appliances and reduces the risk of electrical fires in homes.
- 30. PSLV : Polar Satellite Launch Vehicle. GSLV : Geosynchronous Satellite Launch Vehicle.
- 31. A phyllode is a modified petiole (leaf stalk) that becomes flattened and leaf-like in appearance and function. In plants like Acacia auriculiformis, the petioles expand and become green to form structures that resemble leaves. These phyllodes carry out the functions normally performed by leaves, particularly photosynthesis. The actual leaves in such plants are either absent or reduced to small scales. Phyllodes are an adaptation that allows plants to reduce water loss while maintaining the ability to photosynthesize, making them particularly useful in plants growing in dry environments.
- 32. When water is heated, the level of water in the container increases. This occurs because heat causes the water to expand, increasing its volume. As the water molecules gain thermal energy, they move faster and spread out, requiring more space. Therefore, the same mass of water occupies a larger volume when heated, causing the water level to rise in the container or refill vessel.
- 33. Living things: Living things use energy. They move or change shape. Eg: Humans, insects, plants, animals etc. Non-living things: Do not move by themselves, grow or reproduce. Eg: Rocks, car, pencils etc.
- 34. Your friend's statement is incorrect. Velocity, not acceleration, gives an idea of how fast the position changes. Velocity is defined as the rate of change of position or displacement with respect to time, so it directly tells us how quickly an object's position is changing. Acceleration, on the other hand, gives an idea of how fast the velocity changes with respect to time. Acceleration is the rate of change of velocity, not position. For example, when a car speeds up, its velocity is increasing, and we say the car has acceleration. Therefore, to correct your friend, you should say that velocity gives the idea of how fast the position changes, while acceleration gives the idea of how fast the velocity changes.
- 35. Difference between Antiseptic and Disinfectants Antiseptic Disinfectants 1. All antiseptic are disinfectants 1. All disinfectants are not antiseptic 2. It can be applied on the live tissue 2. It can be apply on in animate object 3. E.g. skin / Mucous 3. E.g. Surface, lab working tables, floor.
Brain Grain · braingrain.in
Science — Practice Paper · Set 2
Class: 7Samacheer KalviMax Marks: 59
Name: ____________________Reg No: ____________
Part I — Multiple Choice Questions 10 × 1 = 10
Choose the correct answer. (Answer all questions.)
1.Light is a form of ____A. matterB. energyC. mediumD. partical[1]
2.Write the binomial name ofA. Human beingB. Paddy[1]
3.Suitable term for the various components of cell is _________A. TissueB. NucleusC. CellD. Cell organelle[1]
4.Which of the following is an example of a metal?A. IronB. OxygenC. HeliumD. Water[1]
5.Mercury is often used in laboratory thermometers because itA. is a harmless liquidB. is silvery in colour and is attractive in appearanceC. Expands uniformlyD. is a low cost liquid[1]
6.Which software is used to create symbolsA. PhotoshopB. IllustratorC. Vector GraphicsD. Photostory[1]
7.Who proposed the five kingdom of classification?A. AristotleB. LinnaeusC. WhitakarD. Plato[1]
8.Light travels only in a ______ .It is because of this property that.A. curved line, shadowsB. straight line, shadowsC. straight line, reflectionD. curved line and then straight line, shadows[1]
9.Light that hits a mirror gets ______A. TransmittedB. ReflectedC. AbsorbedD. Refracted[1]
10.When a woolen yarn is knitted to get a sweater, the change can be classified as _________A. physical changeB. chemical changeC. endothermic changeD. exothermic change[1]
Part II — Fill in the Blanks 5 × 1 = 5
Fill in the blanks. (Answer all questions.)
11.Typhoid: Bacteria:: Hepatitis: _________[1]
12.Tincture:: ______, Histamine : : _______[1]
13.Two plane mirrors M1 and M2 are placed perpendicular with each other, as shown in figure. The ray AB makes an angle 39° with the plane mirror M , then The reflected rays are _________, ____________ The incident rays are _________, ____________ What is the angle of incident corresponding to the ray BC? What is the angle of reflection corresponding to the ray CD[1]
14.A group of people living together in a particular area is called ______[1]
15.Nylon :melts on heating:: Silk: ______[1]
Part III — True or False 5 × 1 = 5
Write True or False. (Answer all questions.)
16.A ball of iron floats in mercury.[1]
17.Wool is the fibre derived from the silk worm.[1]
18.A substance which contains less number of molecules per unit volume is said to be denser.[1]
19.Pencillin is the best medicine for curing Anthrax.[1]
20.A complete flower has four whorls.[1]
Part IV — Short Answer Questions 12 × 2 = 24
Answer briefly. (Answer all questions.)
21.What does cell membrane do?[2]
22.Who invented the Ahimsa silk?[2]
23.How to close a document?[2]
24.Write correct sequence from cell to organism?[2]
25.Write down the formula used to find the volume of a cylinder.[2]
26.The only evidence of the big bang theory is[2]
27.What is Tux Paint ?[2]
28.Which of these fabrics dries the fastest? The cotton cloth or the umbrella cloth?[2]
29.Mention any two exothermic reactions.[2]
30.Tuberculosis is caused by the bacterium .[2]
31.Classify the following as elements and compounds. Water, common salt, sugar, carbon dioxide, iodine and lithium[2]
32.Study the pictures given and write the differences between cells that you observe in the given table[2]
Part V — Long Answer Questions 3 × 5 = 15
Answer in detail. (Answer all questions.)
33.What first aid will you provide in the case of bruises?[5]
34.What are the difference between luminous and non-luminous objects? Give two examples of each.[5]
35.When the velocity of the object is increasing by 20 m/s the acceleration is 20 m/s2 When the velocity of the object is decreasing by 20 m/s the deceleration is 20 m/s2.[5]
🔑 Show Answer Key — Set 2
- 1. (b) energy
- 2. Binomial name (a) Human being – Homo sapiens (b) Paddy – Oryza sativa
- 3. The suitable term for the various components of a cell is cell organelle. Cell organelles are specialized structures within the cell that perform specific functions necessary for the cell to survive and function properly. Examples of cell organelles include the nucleus, mitochondria, chloroplast, endoplasmic reticulum, Golgi apparatus, lysosomes, and ribosomes. Each organelle has a distinct structure and carries out particular tasks such as energy production, protein synthesis, storage, or transport of materials. The term organelle literally means a small organ, which reflects how these structures work like tiny organs within the cell to maintain life processes. Understanding cell organelles is fundamental to cell biology as they are the functional units that enable cells to perform all necessary activities for growth, metabolism, and reproduction.
- 4. (a) Iron
- 5. (c) Expands uniformly
- 6. (c) Vector Graphics
- 7. (c) Whitakar
- 8. (b) straight line, shadows
- 9. (b) Reflected
- 10. (a) physical change
- 11. Vims.
- 12. Antiseptic, Chemical messenger
- 13. BC, CD AB, BC \(\lfloor i\) = 39° \(\lfloor r\) = 39°
- 14. Community
- 15. Burns on heating.
- 16. This statement is true. A ball of iron floats in mercury. Mercury is a liquid metal with a very high density of approximately 13.6 grams per cubic centimeter, which is much greater than the density of iron at approximately 7.8 grams per cubic centimeter. Since mercury is denser than iron, an iron ball will float on the surface of mercury rather than sink. This demonstrates the principle that objects float in liquids that are denser than themselves.
- 17. False. Wool is not the fibre derived from the silk worm. Silk is the fibre derived from the silk worm. Wool is actually obtained from the fleece of sheep and goats through a process called shearing. Silk, on the other hand, is produced by silk worms, which are the larvae of the silk moth. The silk worm secretes a continuous filament of protein called sericin, which hardens into silk fibre. This silk fibre is obtained by unwinding the cocoon that the silk worm spins around itself. Therefore, the correct statement is that silk is the fibre derived from the silk worm, not wool.
- 18. This statement is false. The correct statement is that a substance which contains more number of molecules per unit volume is said to be denser. Density is a measure of how closely packed the molecules or atoms of a substance are within a given volume. When a substance has more molecules packed into the same unit volume, it means the molecules are closer together, resulting in greater density. Conversely, a substance with fewer molecules per unit volume has lower density because its molecules are more spread out. For example, iron has a higher density than wood because iron atoms are packed more tightly together in the same volume compared to wood molecules. This relationship between molecular packing and density is fundamental to understanding why some objects sink while others float in different liquids.
- 19. True. Penicillin is the best medicine for curing Anthrax. Anthrax is a serious infectious disease caused by the bacterium Bacillus anthracis. Penicillin is an antibiotic that effectively kills this bacterium and is considered the primary treatment for anthrax infection. When administered promptly after exposure or infection, penicillin can prevent the disease from progressing and can cure infected individuals. This antibiotic works by disrupting the bacterial cell wall, leading to the death of the pathogenic bacteria. Early treatment with penicillin is crucial for successful recovery from anthrax.
- 20. True. A complete flower has four whorls, which are concentric rings of floral parts arranged around the receptacle. These four whorls are the calyx (sepals), corolla (petals), androecium (stamens), and gynoecium (carpels). Each whorl has a specific function in the reproduction and protection of the flower. The calyx protects the flower bud, the corolla attracts pollinators, the androecium produces pollen, and the gynoecium contains the ovules for seed production.
- 21. The cell membrane acts as a boundary that separates the internal contents of the cell from the external environment. It protects the cell by controlling what enters and exits the cell. The cell membrane is selectively permeable, meaning it allows certain substances to pass through while preventing others from entering or leaving. This protective barrier is essential for maintaining the cell's integrity and allowing it to function properly.
- 22. Kusuma Rajaiah, a Government officer from Andhra Pradesh, proposed the Ahimsa method of silk production. This innovative approach aims to produce silk without killing the silkworms. In traditional silk manufacturing, cocoons are boiled to extract the silk threads, which results in the death of the pupae inside. Ahimsa silk, also known as Peace silk, uses a humane alternative where silkworms are allowed to hatch naturally from their cocoons, and only the vacant cocoons are then used for silk production. This method has gained support from people concerned with animal welfare while still allowing for the production of high-quality silk fabric.
- 23. To close a document in a text document software application, you can use either of two methods. The first method is to select the File menu from the menu bar at the top of the window, then click on the Close command option. The second method is to click the Close icon if it is visible on the Standard toolbar, which typically appears as an X button. Either approach will close the current document you are working on. If you have made unsaved changes to the document, the application will usually prompt you to save your work before closing.
- 24. The correct sequence from cell to organism is: Cell → Tissue → Organ → Organ System → Organism. This hierarchical organization shows how cells combine to form tissues, tissues organize into organs, organs work together in organ systems, and finally organ systems function together to create a complete living organism.
- 25. The formula used to find the volume of a cylinder is Volume = πr^2h, where 'π' (pi) is a mathematical constant approximately equal to 3.14159, 'r' is the radius of the circular base of the cylinder, and 'h' is the height of the cylinder. This formula calculates the amount of three-dimensional space occupied by the cylinder.
- 26. The only evidence of the Big Bang theory is a faint glow in space called the cosmic microwave background radiation. This radiation is the leftover heat from the extremely hot early universe and was discovered in 1964. The cosmic microwave background fills all of space uniformly and provides strong observational support for the Big Bang theory, as it is exactly what scientists predicted would remain if the universe had indeed begun from an extremely hot, dense state and has been expanding and cooling ever since.
- 27. Tux Paint is a free drawing program designed for young children to create digital artwork. It provides a simple and user-friendly interface with various drawing tools such as brushes, pencils, shapes, and colors. The program is open source software, meaning it is freely available for anyone to use and modify. Tux Paint helps develop creativity and artistic skills in children by allowing them to draw, paint, and create digital images in an interactive and enjoyable manner.
- 28. Umbrella cloth dries the fastest compared to cotton cloth. This is because umbrella cloth, made of synthetic fibres like nylon or polyester, does not absorb water and allows it to remain on the surface where it can evaporate quickly. Cotton cloth, being a natural and absorbent fibre, absorbs water into its structure, which takes longer to dry as the water must evaporate from within the fabric. The water-resistant nature of synthetic umbrella fabric enables faster drying compared to the water-absorbing properties of cotton.
- 29. Two examples of exothermic reactions are the burning of a magnesium ribbon and the burning of a candle. In both these reactions, heat energy is released to the surroundings, causing an increase in temperature. When magnesium ribbon burns in air, it produces magnesium oxide and releases a large amount of heat and light. Similarly, when a candle burns, the wax undergoes combustion and releases heat and light energy to the surroundings.
- 30. Tuberculosis is a serious infectious disease caused by a specific type of bacterium known as Mycobacterium tuberculosis. This bacterium primarily affects the lungs but can also spread to other parts of the body, such as the brain, spine, and kidneys. Tuberculosis is typically spread through the air when an infected person coughs, sneezes, or speaks, releasing tiny droplets containing the bacteria. Prompt diagnosis and treatment with antibiotics are essential to cure the disease and prevent its transmission.
- 31. Elements: Iodine, Lithium. Compounds: Water, Common salt, Sugar, Carbon dioxide. Elements are pure substances made up of only one type of atom and cannot be broken down into simpler substances by chemical means. Iodine and lithium are both elements because they consist of only one type of atom each. Compounds, on the other hand, are pure substances formed when atoms of two or more different elements combine chemically in fixed proportions. Water (H₂O) is a compound of hydrogen and oxygen, common salt (NaCl) is a compound of sodium and chlorine, sugar (C₁₂H₂₂O₁₁) is a compound of carbon, hydrogen, and oxygen, and carbon dioxide (CO₂) is a compound of carbon and oxygen. Compounds have different properties from the elements that make them up. Elements are pure substances made up of only one type of atom and cannot be broken down into simpler substances by chemical means. Iodine and lithium are both elements because they consist of only one type of atom each. Compounds, on the other hand, are pure substances formed when atoms of two or more different elements combine chemically in fixed proportions. Water (H₂O) is a compound of hydrogen and oxygen, common salt (NaCl) is a compound of sodium and chlorine, sugar (C₁₂H₂₂O₁₁) is a compound of carbon, hydrogen, and oxygen, and carbon dioxide (CO₂) is a compound of carbon and oxygen. Compounds have different properties from the elements that make them up. Elements are pure substances made up of only one type of atom and cannot be broken down into simpler substances by chemical means. Iodine and lithium are both elements because they consist of only one type of atom each. Compounds, on the other hand, are pure substances formed when atoms of two or more different elements combine chemically in fixed proportions. Water (H₂O) is a compound of hydrogen and oxygen, common salt (NaCl) is a compound of sodium and chlorine, sugar (C₁₂H₂₂O₁₁) is a compound of carbon, hydrogen, and oxygen, and carbon dioxide (CO₂) is a compound of carbon and oxygen. Compounds have different properties from the elements that make them up. Elements are pure substances made up of only one type of atom and cannot be broken down into simpler substances by chemical means. Iodine and lithium are both elements because they consist of only one type of atom each. Compounds, on the other hand, are pure substances formed when atoms of two or more different elements combine chemically in fixed proportions. Water (H₂O) is a compound of hydrogen and oxygen, common salt (NaCl) is a compound of sodium and chlorine, sugar (C₁₂H₂₂O₁₁) is a compound of carbon, hydrogen, and oxygen, and carbon dioxide (CO₂) is a compound of carbon and oxygen. Compounds have different properties from the elements that make them up.
- 32. (refer textbook)
- 33. Bruises are injuries that result from blunt force trauma causing damage to the skin and underlying tissues without breaking the skin surface. When a person sustains a bruise, the affected area should be immediately washed with cold running water to reduce inflammation and numb the pain. After washing, the wound should be cleaned gently and an antiseptic cream should be applied to prevent infection and promote healing. Cold water application helps constrict blood vessels, reducing bleeding into the tissues and minimizing swelling. The bruised area should be kept elevated if possible to reduce further accumulation of blood. If the bruise is severe or accompanied by significant swelling or pain, medical attention should be sought to rule out deeper tissue damage or fractures.
- 34. Luminous objects are all objects which emit light energy by themselves. These objects produce their own light through various processes such as combustion, incandescence, or chemical reactions. Non-luminous objects are all objects which do not emit light energy of their own, but reflect the light energy falling on them and hence become visible. These objects are visible only because they reflect light from luminous sources. Examples of luminous objects include the Sun, stars, electric bulbs, torches, and burning candles. Examples of non-luminous objects include the Moon, planets, trees, houses, stones, metals, and most everyday objects we see around us. The key difference is that luminous objects are sources of light, while non-luminous objects are visible only because they reflect light from other sources.
- 35. When the velocity of an object is decreasing, it is undergoing deceleration, also known as negative acceleration. If the velocity of the object is decreasing by 20 m/s, it means that for every second that passes, the object's speed is reducing by 20 meters per second. Therefore, the deceleration is 20 m/s^2. This indicates a constant rate at which the object is slowing down. For example, if an object is moving at 60 m/s and then its velocity decreases by 20 m/s, after one second its velocity will be 40 m/s, and after another second, it will be 20 m/s, assuming constant deceleration.
Brain Grain · braingrain.in
Science — Practice Paper · Set 3
Class: 7Samacheer KalviMax Marks: 59
Name: ____________________Reg No: ____________
Part I — Multiple Choice Questions 10 × 1 = 10
Choose the correct answer. (Answer all questions.)
1.Which is the example for an Wimation ?A. sound communicationB. visual communicationC. vector communicationD. raster communication[1]
2.Study the electric circuit below. Which of the following switches should be closed so that only two bulbs will light up.A. SI, S2 and S4 onlyB. SI, S3 and S5 onlyC. S2, S3 and S4 onlyD. S2, S3 and S5 only[1]
3.Which parts of the goat and sheep is used for manufacturing clothes?A. LegB. HandC. HairD. Head[1]
4.Small amounts of electrical current are measured in milliampere (mA). How many milliampere are there in 0.25 A ?A. 2.5 mAB. 25 mAC. 250 mAD. 2500 mA[1]
5.Draw the following regularly shaped figures on a graph sheet and find their area by the graphical method. Also, find their area using appropriate formula. Compare the results obtained in two methods by tabulating them.A. A rectangle whose length is 12 cm and breadth is 4 cm.B. A square whose side is 6 cm.C. A circle whose radius is 7 cm.D. A triangle whose base is 6 cm and height is 8 cm.[1]
6.The atomic number of an atom is __________A. Number of neutronsB. Number of protonsC. Total number of protons and neutronsD. Number of atoms[1]
7.1. Animations(a) 3D 2. Raster(b) Visual Communication 3. Vector(c) Pixels 4. Virtual Reality(d) Microsoft Photostory 5. Video Story(e) Illustrator[1]
8.The Keyboard shortcut is used to cut the selected textA. Ctrl+ cB. Ctrl+vC. Ctrl+xD. Ctrl+A[1]
9.1. Rabie(a) Salmonella 2. Cholera(b) Yellow urine 3. Tuberculosis(c) Cramps in legs 4. Hepatitis(d) Hydrophobia 5. Typhoid(e) Mycobacterium[1]
10.Pollinators areA. WindB. WaterC. InsectD. All the above[1]
Part II — Fill in the Blanks 5 × 1 = 5
Fill in the blanks. (Answer all questions.)
11.Chloroplast: photosynthesis :: mitochondria :________[1]
12.Physical Change: Boiling::Chemical Change: ________[1]
13.______ is an example of polyester fabric. ______ are used to identify different types of plastics. A ______ is a long chain made up of many repeated small units called monomers. The fully natural fibreis called ______ A natural fibre obtained by boiling of cocoons is called ______[1]
14.Liquid : Litre :: Solid : _________[1]
15.Adipose : tissue :: eye :_________[1]
Part III — True or False 5 × 1 = 5
Write True or False. (Answer all questions.)
16.Cell membrane is fully permeable.[1]
17.Atoms cannot exist alone; they can only exist as groups called molecules.[1]
18.Animals are the greatest gift of nature.[1]
19.Galilio accepted the Geo-centric model.[1]
20.An atom is electrically neutral.[1]
Part IV — Short Answer Questions 12 × 2 = 24
Answer briefly. (Answer all questions.)
21.A plastic bag dumped in the soil stays without breaking down for 500years. If a new generation starts in every 30 years, how many generations would it take to see the plastic bag finally broken down?[2]
22.What are the agents of pollination?[2]
23.Write the symptoms of Anthrax.[2]
24.The Tamil Nadu Government has banned the use of one-time use throw away plastics. Why do you think this is important?[2]
25.Define an atom.[2]
26.Give any two communicable disease, which spreads in your locality during monsoon?[2]
27.What are the main things in a nucleus?[2]
28.What is right alignment?[2]
29.Name few insulators.[2]
30.List out the five kingdoms classification.[2]
31.Elements contains two or more kinds of atoms and compounds contains only one kinds of atoms.[2]
32.Measure your body temperature. Wash the thermometer preferably with an antiseptic solution. Hold it firmly by the end and give it a few jerks. These jerks will bring the level of Mercury down. Ensure that it falls below 35°C (95°F). Now place the thermometer under your tongue or arm pit. After one minute, take the thermometer out and note the reading. It tells you your body temperature. What did you record as your body temperature?[2]
Part V — Long Answer Questions 3 × 5 = 15
Answer in detail. (Answer all questions.)
33.Synthetic or Natural Fibres : The teacher can give the learner a piece of each and every type of fibre. The learner can feel the fibre and write down the name of the fibre and state whether it is natural or synthetic fibre.[5]
34.Write a short note on nucleus.[5]
35.A person is looking at the image of a tree in a mirror placed 3.5 m in front of him. Given that the tree is at 0.5 m behind his eyes. Find the distance between the image of the tree and his eyes. What are needed to see an object?[5]
🔑 Show Answer Key — Set 3
- 1. (b) visual communication
- 2. (c) S2, S3 and S4 only
- 3. (c) Hair
- 4. (c) 250 mA
- 5. To find the area of regularly shaped figures like squares, rectangles, or triangles using the graphical method, first draw the figure accurately on a graph sheet. Then, count the number of complete squares inside the figure. Next, count the number of incomplete squares that are more than half-filled and divide this number by two. Finally, add the number of complete squares and the number of half-filled squares to get the total area in square units. For comparison, calculate the area using the standard formula for that shape (e.g., length x width for a rectangle, 1/2 x base x height for a triangle). Tabulate both results to compare their accuracy. The graphical method provides an approximate area, while the formula gives the precise area.
- 6. (b) Number of protons
- 7. b c e a d
- 8. (c) Ctrl+x
- 9. d c e b a
- 10. d) All the above
- 11. Respiration.
- 12. Burning.
- 13. Raincoat Resin codes polymer plant fibre silk
- 14. cm 3
- 15. Organ
- 16. False. The cell membrane is not fully permeable. The cell membrane is selectively permeable, also called semi-permeable. This means that the cell membrane allows some substances to pass through it while preventing others from crossing. The cell membrane controls which molecules and ions can enter or exit the cell based on the cell's needs. This selective permeability is crucial for maintaining the internal environment of the cell and protecting it from harmful substances.
- 17. This statement is true. While individual atoms do exist and have their own properties, most atoms in nature do not remain isolated. Instead, atoms combine with one another through chemical bonding to form molecules, which are the smallest units of compounds that retain the chemical properties of the substance. For example, oxygen atoms combine to form oxygen molecules (O₂), and hydrogen atoms combine to form hydrogen molecules (H₂). Even noble gases like helium and neon, which are chemically inert, exist as single atoms in their elemental form, but in most other cases, atoms group together as molecules to achieve greater stability.
- 18. True. Animals are indeed the greatest gift of nature because they provide us with numerous essential resources and services. Animals supply us with food such as meat, milk, and eggs, which are rich sources of protein and nutrients necessary for human survival and health. They also provide us with valuable materials like wool, silk, leather, and fur that are used to make clothing and other products. Additionally, animals play crucial roles in maintaining ecological balance by pollinating plants, controlling pest populations, and contributing to nutrient cycling in ecosystems. Many animals also serve as companions and provide emotional support to humans. Furthermore, animals have been instrumental in advancing human knowledge through scientific research and medical discoveries.
- 19. False. The correct statement is that Galileo did not accept the geocentric model. Galileo supported the heliocentric model, which places the Sun at the center of the solar system with planets orbiting around it. Through his observations with the telescope, Galileo discovered evidence that supported the heliocentric theory, such as the moons of Jupiter and the phases of Venus. His support for the heliocentric model was significant in the scientific revolution and challenged the prevailing geocentric view of his time.
- 20. True. An atom is electrically neutral because it contains equal numbers of protons and electrons. Protons are positively charged particles located in the nucleus, while electrons are negatively charged particles that orbit around the nucleus. Since the positive charge of protons is equal in magnitude to the negative charge of electrons, the net charge of an atom is zero, making it electrically neutral. For example, a carbon atom has six protons and six electrons, so the positive and negative charges cancel each other out, resulting in a neutral atom. If an atom loses or gains electrons, it becomes an ion and is no longer electrically neutral.
- 21. It would take 16 to 17 generations to see the plastic bag finally broken down. XIII.
- 22. The agents of pollination are insects, wind, water, and animals. Insects such as bees, butterflies, and moths visit flowers to collect nectar and pollen, and in the process, they transfer pollen from flower to flower. Wind carries light pollen grains from one flower to another in wind-pollinated plants. Water can transport pollen in aquatic plants and some plants growing near water bodies. Animals such as birds and mammals also help in pollination by visiting flowers for food and inadvertently transferring pollen on their bodies. Each agent is suited to pollinate specific types of flowers based on flower structure and characteristics.
- 23. The symptoms of Anthrax include fever, cough, and shortness of breath, which are similar to those of typical pneumonia. Infected individuals may also experience other symptoms such as nausea, vomiting, and diarrhoea. In some cases, anthrax can cause skin lesions or sores if the infection enters through the skin. The severity of symptoms depends on the route of infection and how quickly treatment is initiated. If left untreated, anthrax can progress to more serious complications and become life-threatening. Therefore, recognizing these symptoms early and seeking medical treatment promptly is essential for recovery.
- 24. The Tamil Nadu Government's ban on one-time use throw away plastics is important because it helps reduce the accumulation of plastic waste in the environment. Single-use plastics such as bags, bottles, and packaging materials are used for only a few minutes but persist in nature for hundreds of years, causing severe environmental pollution. By banning these plastics, the government aims to decrease the amount of non-biodegradable waste that ends up in landfills and oceans, protecting wildlife from ingesting plastic and suffering harm. This ban encourages people to use alternative materials like cloth bags and paper products, promoting sustainable practices and reducing the negative consequences of plastics on ecosystems, animals, and human health.
- 25. An atom is the smallest particle of a chemical element that retains its chemical properties and cannot be broken down further by chemical means. It is the basic building block of all matter. An atom consists of a nucleus containing protons and neutrons, surrounded by electrons in electron shells. Atoms of different elements have different numbers of protons, which determines their identity and chemical behavior. Atoms combine with other atoms to form molecules and compounds.
- 26. Two communicable diseases that commonly spread in localities during the monsoon season are cholera and diarrhea. Cholera is a bacterial infection spread through contaminated water and food, causing severe dehydration and watery stools. Diarrhea is also transmitted through contaminated food and water sources, which become more prevalent during monsoon due to poor sanitation and water logging. Both diseases are water-borne and spread rapidly in areas with inadequate drainage and sanitation facilities during heavy rainfall.
- 27. The main components found inside a nucleus are the nuclear envelope, nucleolus, and chromatin body. The nuclear envelope is the double membrane that surrounds the nucleus and controls the movement of materials between the nucleus and the cytoplasm. The nucleolus is a dense region within the nucleus where ribosomal RNA is synthesized and ribosomal subunits are assembled. The chromatin body consists of DNA and proteins that are loosely arranged in the nucleus and contain the genetic information of the cell. During cell division, the chromatin condenses to form visible chromosomes.
- 28. Right alignment is a text formatting technique where text or content is aligned along the right margin or right edge of a page or containing element. When right alignment is applied, the text starts from the right side and extends toward the left, creating a flush right edge while the left edge remains uneven or ragged. This formatting is commonly used in documents, presentations, and web pages to create specific visual layouts or to align text in particular directions, such as in right-to-left languages or for stylistic purposes in document design.
- 29. Some insulators are rubber, wood, plastic, and glass. Insulators are materials that do not allow electric current to flow through them easily because they have very few free electrons. Other common insulators include paper, cloth, ceramic, and air. These materials are used to cover conducting wires and to prevent unwanted flow of electric current, thereby providing safety in electrical circuits and appliances.
- 30. The five kingdoms classification system divides all living organisms into five major groups. These kingdoms are Monera, which includes prokaryotic organisms like bacteria; Protista, which contains unicellular and simple multicellular eukaryotes; Fungi, comprising organisms that are heterotrophic and obtain nutrition from dead or living matter; Plantae, which includes all multicellular photosynthetic plants; and Animalia, which contains all multicellular heterotrophic animals. This classification system is based on characteristics such as cell structure, mode of nutrition, and body organization.
- 31. This statement is incorrect. The correct statement is: Elements contain only one kind of atom, while compounds contain two or more kinds of atoms. An element is a pure substance made up of only one type of atom. For example, pure oxygen contains only oxygen atoms, and pure iron contains only iron atoms. A compound, however, is formed when two or more different elements combine chemically in a fixed proportion. For instance, water is a compound made up of hydrogen atoms and oxygen atoms combined in a fixed ratio of 2:1. Similarly, sodium chloride is a compound containing sodium atoms and chlorine atoms. The key difference is that elements have atoms of only one type, whereas compounds have atoms of two or more different types chemically bonded together.
- 32. The body temperature recorded was 37°C. This is the normal human body temperature measured using a clinical thermometer. The thermometer was placed under the tongue or armpit for one minute to allow it to reach thermal equilibrium with the body, ensuring an accurate reading. Normal body temperature in humans typically ranges from 36.5°C to 37.5°C, with 37°C being the standard average value. This temperature is maintained by the body's thermoregulatory mechanisms and is essential for proper functioning of all biological processes.
- 33. Natural and synthetic fibres can be identified and classified based on their origin and properties. Jute is a natural fibre obtained from plants and is used for making ropes and bags. Cotton is a natural fibre derived from cotton plants and is widely used in textiles for clothing. Rayon is a synthetic fibre manufactured from cellulose and is used as an alternative to natural fibres in fabrics. Wool is a natural fibre obtained from sheep and other animals, known for its warmth and insulation properties. Polyester is a synthetic fibre created through chemical processes and is used in various applications due to its durability and water-resistant properties. Natural fibres come from plants and animals, while synthetic fibres are manufactured through chemical processes in industries. Each type of fibre has distinct characteristics that make it suitable for different purposes in textiles and other applications.
- 34. The nucleus is a membrane-bound organelle found in the cytoplasm of both plant and animal cells. It is surrounded by a double-layered nuclear envelope that controls the movement of materials between the nucleus and cytoplasm. Inside the nucleus, there are one or two nucleoli, which are sites of ribosome production, and a chromatin body composed of DNA and proteins. The chromatin body stores all the genetic information of the cell in the form of genes. The nucleus performs several critical functions in the cell. It controls all the metabolic processes and chemical reactions that occur inside the cell by regulating gene expression. The nucleus is responsible for the inheritance of characteristics from one generation to another through the transmission of genetic material during reproduction. During cell division, the chromatin condenses into visible chromosomes that carry genetic instructions. The nucleus essentially acts as the control center of the cell, directing all cellular activities and ensuring the continuity of life through heredity.
- 35. Distance between the person and the mirror = 3.5 m Distance between the person and tree (object) = 0.5 m The image formed in the mirror = 4 m The distance between the image of the tree and his eyes = 4 + 3.5 = 7.5