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.Which option is used in the Microsoft Photostory to upload the photos?A. Begin a StoryB. Import PicturesC. SettingsD. View your Story[1]
2.The largest division of the living world isA. OrderB. KingdomC. PhylumD. Family[1]
3.Aspirin is ______A. AntibioticB. AntipyreticC. SedativeD. Psychedelic[1]
4.Define the following termsA. Incident rayB. Reflected rayC. NormalD. Angle of incidence[1]
5.Oxygen, hydrogen, and sulphur are examples of which of the following?A. MetalsB. Non-metalsC. MetalloidsD. Inert gases[1]
6.Reflection occurs , when the lightA. about to reach a surfaceB. approaches a surfaceC. passes through a surfaceD. None Of these[1]
7.SI unit of density isA. kg/m 2B. kg/m 3C. kg/mD. g/m 3[1]
8.PET is the acronym for ________A. PolyesterB. Polyester and teryleneC. Polyethylene terephthalateD. Polyetheneterylene[1]
9.______ surface reflects the light wellA. WaterB. Compact discC. MirrorD. Stone[1]
10.Which of the following figures represent uniform motion of a moving object correctly?[1]
Part II — Fill in the Blanks 5 × 1 = 5
Fill in the blanks. (Answer all questions.)
11.Volume of irregularly shaped objects are measured using the law of ___________ One cubic metre is equal to ___________ cubic centimetre. Density of mercury is ___________ One astronomical unit is equal to ___________ The area of a leaf can be measured using a ___________[1]
12.Forest fire: ________ change::Change in period in a school: periodic change[1]
13.Water : pipe : : Electric current: ______.[1]
14.First viral disease detected in human being was : _____ (Yellow fever / dengue fever)[1]
15.Water: pipe : Electric current: : ______[1]
Part III — True or False 5 × 1 = 5
Write True or False. (Answer all questions.)
16.Pencillin is the best medicine for curing Anthrax.[1]
17.Ribosomes are small organelles with a membrane.[1]
18.Burning wood and coal causes pollution of air.[1]
19.All fuels form flame.[1]
20.We see planets because they reflect light from the sun[1]
Part IV — Short Answer Questions 12 × 2 = 24
Answer briefly. (Answer all questions.)
21.Who invented the Ahimsa silk?[2]
22.Give the expansions of PSLV and GSLV.[2]
23.Define the density of objects.[2]
24.Iam green colour box with garbage. Who am I ?[2]
25.Some known objects are shown, also the broken particles of the objects are shown. Name the articles or objects you see here? Also try to write What each of it made of?[2]
26.Study the pictures given and write the differences between cells that you observe in the given table[2]
27.Write correct sequence from cell to organism?[2]
28.What is Tux Math?[2]
29.What are the two important parts of a flower?[2]
30.Chicken pox also known as Leucoderma.[2]
31.Observe the picture and list down the changes that are accompanied in the picture.[2]
32.Is solar eclipse a periodic change? Give your reason.[2]
Part V — Long Answer Questions 3 × 5 = 15
Answer in detail. (Answer all questions.)
33.Arul and Aakash were doing an experiment in which water was to be heated in a beaker. Arul kept the beaker near the wick in the yellow part of candle flame. Aakash kept the beaker in the outer most part to the flame. Whose water will get heated in a shorter time?[5]
34.Describe the different ways in which we can write the symbols of elements. Give appropriate examples.[5]
35.What is selecting text?[5]
🔑 Show Answer Key — Set 1
- 1. (b) Import Pictures
- 2. (b) Kingdom
- 3. (b) Antipyretic
- 4. The following are important terms related to reflection of light. Incident ray is the ray of light that falls on the surface of the reflecting material. It is the incoming light ray that strikes the mirror or reflective surface. Reflected ray is the ray of light that comes from the point where the incident ray falls on the reflecting material. It is the outgoing light ray that bounces off the mirror after reflection. Normal is the perpendicular line drawn from the point of incidence to the plane of the reflecting surface. It serves as a reference line for measuring angles in reflection. Angle of incidence is the angle formed between the incident ray and the normal at the point of incidenc…
- 5. (b) Non-metals
- 6. (b) approaches a surface
- 7. (b) kg/m 3
- 8. (c) Polyethylene terephthalate
- 9. (c) Mirror
- 10. Uniform motion is defined as motion in which an object covers equal distances in equal intervals of time, moving along a straight line. Therefore, the figure that correctly represents uniform motion will show an object moving at a constant speed in a single, unchanging direction. This is typically depicted as a straight line on a distance-time graph with a constant slope, or a position-time graph with a constant positive slope, indicating that the object's position changes by the same amount in each successive time interval.
- 11. Archimedes 10,00,000 or 106 6 13,600 kg/m 3 1.496×10 11 m graph sheet
- 12. Non-periodic.
- 13. wire
- 14. Yellow fever.
- 15. Wire
- 16. 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.
- 17. False. Ribosomes are small organelles without a membrane. Ribosomes are non-membrane-bound organelles found in all cells, both prokaryotic and eukaryotic. They are composed of ribosomal RNA and proteins and are responsible for protein synthesis. Because ribosomes lack a surrounding membrane, they are classified as non-membrane-bound organelles, unlike organelles such as the mitochondria or endoplasmic reticulum which have membranes.
- 18. True. Burning wood and coal causes pollution of air. When wood and coal are burned, they release harmful gases and particles into the atmosphere. These include carbon dioxide, which contributes to climate change, carbon monoxide, which is toxic, and particulate matter that can damage respiratory systems. Burning fossil fuels like coal also releases sulfur dioxide and nitrogen oxides, which contribute to acid rain and smog, making air pollution a serious environmental and health concern.
- 19. This statement is false. All fuels do not form flame. While many fuels like wood, coal, and candles produce visible flames when they burn, some fuels burn without producing a flame. For example, charcoal can burn with a glow but without a visible flame. A flame is produced only when gases are released during combustion and burn in air, so not all burning fuels necessarily produce flames.
- 20. True
- 21. 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.
- 22. PSLV : Polar Satellite Launch Vehicle. GSLV : Geosynchronous Satellite Launch Vehicle.
- 23. Density of a substance is defined as the mass of the substance contained in unit volume. It is a derived physical quantity that tells us how much mass is packed into a given volume. Density is calculated by dividing the total mass of an object by its total volume. Objects with higher density are heavier for the same volume, while objects with lower density are lighter for the same volume. For example, iron has a higher density than wood, which is why iron sinks in water while wood floats. The SI unit of density is kilogram per cubic metre (kg/m³).
- 24. A green coloured box used for garbage is known as a biodegradable waste bin. This type of bin is specifically designed to collect organic waste materials that can be decomposed by natural biological processes, such as food scraps, yard waste, and paper products. Proper segregation of waste into biodegradable and non-biodegradable categories is crucial for effective waste management and recycling efforts, helping to reduce landfill burden and promote environmental sustainability.
- 25. The objects shown include a hammer made of iron, bangles made of glass, a tap made of steel, and vessels made of aluminum or steel. Each object is composed of different materials chosen based on their properties and suitability for their intended use. Iron is used in hammers because of its strength and durability, allowing it to withstand repeated impacts. Glass is used for bangles because it is transparent, aesthetically pleasing, and can be molded into decorative shapes. Steel is used for taps because of its corrosion resistance and strength, making it suitable for handling water. Aluminum or steel is used for vessels because these metals conduct heat well, are durable, and are easy to…
- 26. (refer textbook)
- 27. 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.
- 28. Tux Math is an open source arcade-style video game designed for learning arithmetic and basic mathematics. It features an engaging game format where players solve mathematical problems to progress through levels and challenges. The game makes learning arithmetic fun and interactive by combining educational content with entertainment. Tux Math helps children develop their computational skills and mathematical reasoning in an enjoyable way.
- 29. The two important parts of a flower are the androecium and the gynoecium. The androecium is the male reproductive part of the flower, consisting of stamens that produce pollen grains. Each stamen has an anther where pollen is produced and a filament that supports the anther. The gynoecium is the female reproductive part of the flower, consisting of the carpel or pistil. The carpel contains the stigma that receives pollen, the style that connects the stigma to the ovary, and the ovary that contains ovules. These two parts are essential for sexual reproduction in flowering plants.
- 30. Chicken pox is also known as varicella. It is a highly contagious viral infection characterized by an itchy rash with small, fluid-filled blisters that appear all over the body. Leucoderma, also known as vitiligo, is a completely different condition that causes patches of skin to lose their pigment or colour. Therefore, the statement that chicken pox is also known as leucoderma is false.
- 31. 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.
- 32. Yes, a solar eclipse is a periodic change. A solar eclipse occurs when the moon comes between the sun and the earth, blocking the sunlight. This phenomenon occurs at regular intervals, though not every month because the moon's orbit is tilted relative to the earth's orbit around the sun. Solar eclipses repeat in a predictable pattern after a definite interval of time, which is the defining characteristic of a periodic change.
- 33. Aakash's water will get heated in a shorter time because he kept his beaker in the outermost part of the flame, which is the hottest non-luminous zone. The non-luminous zone of a candle flame is the region where complete combustion occurs, resulting in the highest temperature. In contrast, Arul kept the beaker near the wick in the yellow luminous part of the flame, which is cooler and produces less heat due to incomplete combustion. The luminous zone appears yellow because of the presence of unburned carbon particles that emit light but do not contribute significantly to heat production. Therefore, the beaker in the non-luminous zone receives more heat energy per unit time, causing the wa…
- 34. The following rules are followed while assigning symbol to an elements: Chemical symbols usually consist of one or two letters. The symbols of most elements correspond to the first letter (which is capitalized) of their English name. For example, the symbol for oxygen is “O” and that for hydrogen is “H”. When there is more than one element that begins with the same letter, their symbols take two letters. The first letter is capitalised while the second letter has a lower case. For example, the names of both hydrogen and helium begin with H. So, hydrogen is represented by the symbol H and Helium by He. Example:
- 35. Selecting text is the process of highlighting text or picking an object in a document or application to prepare it for further action. When a user selects text, they mark a specific portion of content that they want to work with. For example, a user may select text in order to copy it to another location, cut it to remove it from the current position, or move that text to an alternate location within the document or to a different document entirely. Users can also select files or objects they want to view, open, or manipulate. Selection is typically done using the mouse by clicking and dragging across the desired text or by using keyboard shortcuts. Once text is selected, it usually appea…
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.Our living place should beA. OpenB. ClosedC. CleanD. Unclean / Untidy[1]
2.The basic unit of matter is __________A. ElementB. AtomC. MoleculeD. Electron[1]
3.Directions: Please refer to the following instructions: 1st Statement 2nd Statement 1. Oxygen is a element Oxygen cannot be broken down into anything simpler 2. Hydrogen is an element Hydrogen cannot be broken down into anything simpler 3. Air is a compound Air consists of carbon dioxide 4. Air is a mixture of elements only Only nitrogen, oxygen and neon gases exist in air 5. Mercury is solid in room temperature Mercury is a non-metal Answer 1. (A) Both statements are true and the 2nd statement is a correct explanation of the 1st statement. 2. (A) Both statements are true and the 2nd statement is a correct explanation of the 1 st statement. 3. (D) Both statements are false. Correct statement: Air is a mixture of gases. Air consists of Nitrogen Oxygen, CO,, other noble gases. 4. (A) Both statements are true and the 2nd statement is a correct explanation of the 1 st statement. 5. (D) Both statements are false. Correct statement: Mercury is liquid at room temperature. Mercury is a metal. Complete the following table by writing compounds of its constituents.A. Both statements are true and the 2nd statement is a correct explanation of the 1st statement.B. Both statements are true but the 2nd statement is NOT a correct explanation of the 1st statement.C. The 1st statement is false while the 2nd statement is true.D. Both statements are false.[1]
4.In thermometer when bulb comes in contact with hot object, liquid inside itA. expandsB. contractsC. remains sameD. none of above[1]
5.Aakash noticed that the metal latch on gate was difficult to open during hot sunny days. However, this same latch was not difficult to open at night. Aakash observed that the latch and the gate are exposed to the sun during the day.A. Formulate a hypothesis based on the information provided.B. Briefly state how you would test the hypothesis stated in (a).[1]
6.Which is the hottest part in the flame of candle ______A. BlueB. YellowC. BlackD. Way part[1]
7.Approximately species of living organisms found in the earth.A. 8.7 millionB. 8.6 millionC. 8.5 millionD. 8.8 million[1]
8.The Keyboard shortcut is used to copy 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.Which of the following is an example of a metal?A. IronB. OxygenC. HeliumD. Water[1]
Part II — Fill in the Blanks 5 × 1 = 5
Fill in the blanks. (Answer all questions.)
11.Copper: conductor : wood: : _______[1]
12.______,:_______,:_______ are called green house gases[1]
13.________ in 1623, introduced the binomial nomenclature. Species is the ________unit of classification. ________ are non- green and non-photosynthetic in nature. The binomial name of onion is ________ Carolus Linnaeus is known as the Father of ________[1]
14.The male reproductive part of a flower is __________ __________ is the basal swollen part of the Gynoecium. After fertilization the ovule becomes __________ Breathing roots are seen in __________ plants. Onion and Garlic are example of __________[1]
15.___________ and ___________ planets never appear in the mid-night sky.[1]
Part III — True or False 5 × 1 = 5
Write True or False. (Answer all questions.)
16.Salmonella is a unicellular bacteria.[1]
17.Oxygen is necessary for combustion.[1]
18.Refuse (avoid) is the best way to manage plastic.[1]
19.The image formed in a plane mirror is upside down[1]
20.Antibiotics does work for viruses like cold and[1]
Part IV — Short Answer Questions 12 × 2 = 24
Answer briefly. (Answer all questions.)
21.There are eight letters in the word EINSTEIN Write the word in front of a plane mirror shown in diagram Write down how these letters appear in the mirror How many of these letters appear to be different, when the word is reflected? Write down the letters that appear to be the same.[2]
22.We use an umbrella on rainy days. What kind of umbrella do we use?[2]
23.Write the symptoms of Anthrax.[2]
24.Classify the following as metals, non-metals and metalloids Sodium, Bismuth, Silver, Nitrogen, Silicon, carbon, chlorine, Iron, copper.[2]
25.Define fuse.[2]
26.What is the speed of electric current?[2]
27.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]
28.Write two features of protista.[2]
29.What are the characteristics of wool? Give any three.[2]
30.The distance of a person is 30 km and his displacement is 0 km. What do you infer from this?[2]
31.What change occurs in the state of balloon after heating the bottle? Why?[2]
32.What type of change is artificial ripening of fruit?[2]
Part V — Long Answer Questions 3 × 5 = 15
Answer in detail. (Answer all questions.)
33.Why are atomic numbers and mass numbers are always whole numbers ?[5]
34.Write any two merits of Five Kingdom classification.[5]
35.Why do antiseptics differ from disinfectants? Give one example of each.[5]
🔑 Show Answer Key — Set 2
- 1. (c) Clean
- 2. (b) Atom
- 3. (refer textbook)
- 4. (a) expands
- 5. This observation by Aakash demonstrates the principle of thermal expansion in solids. When the metal latch is exposed to the sun during hot days, it absorbs heat energy. This heat causes the internal energy of the iron latch to increase, and the particles of iron begin to move more vigorously. As the particles gain kinetic energy from heating, the distance between them increases, causing the latch to expand. This expansion makes the latch fit more tightly in its frame, making it difficult to open. The volume of the latch increases due to this thermal expansion, but the mass remains constant because no material is added or removed. At night, when the temperature drops, the iron latch cools…
- 6. (a) Blue
- 7. (a) 8.7 million
- 8. (a) Ctrl+c
- 9. d c e b a
- 10. (a) Iron
- 11. Non conductor
- 12. CO 2 , Methane, Chlorofluorocarbons
- 13. Gaspard Bauhin Basic Fungi Hum sativum Modern Taxonomy
- 14. Androecium Ovary seed mangrove Bulb
- 15. Mercury, Venus.
- 16. True. Salmonella is a unicellular bacterium. Bacteria are prokaryotic organisms that consist of a single cell, meaning they are unicellular. Salmonella is a genus of rod-shaped bacteria that can cause food poisoning and other infections in humans and animals. Despite being microscopic and consisting of only one cell, bacteria like Salmonella are capable of carrying out all life processes including nutrition, respiration, growth, and reproduction.
- 17. True. Oxygen is necessary for combustion. Combustion is a chemical reaction that requires three essential elements known as the fire triangle: fuel, heat, and oxygen. Without oxygen, the combustion process cannot occur. This is why fires are extinguished by removing oxygen, such as by using a fire blanket or by displacing air with carbon dioxide or other inert gases.
- 18. True. Refusing to use plastic, or avoiding plastic consumption, is considered the most effective strategy in plastic waste management. This approach is at the top of the waste management hierarchy because it prevents plastic from being produced and used in the first place, eliminating the problem at its source. By refusing single-use plastics such as bags, straws, and packaging, individuals can significantly reduce the amount of plastic waste entering the environment. This is more effective than recycling or reusing plastics because it avoids the energy and resources required for processing and transportation.
- 19. False. The correct statement is: The image formed in a plane mirror is erect. A plane mirror produces an image that is upright and the same size as the object. The image appears to be behind the mirror at a distance equal to the distance of the object in front of the mirror. Although the image is laterally inverted, it is not upside down.
- 20. This statement is false. Antibiotics do not work for viruses like cold and flu. Antibiotics are medicines that kill bacteria or stop their growth, but viruses are different organisms that do not respond to antibiotics. Cold and flu are viral infections, so taking antibiotics for these diseases is ineffective and unnecessary. Using antibiotics when they are not needed can lead to antibiotic resistance, which is a serious public health problem.
- 21. (i)(ii)(iii) 3 letters (E,N,S) (iv) I,T
- 22. On rainy days, we use umbrellas made of nylon or polyester fabric. These synthetic materials are preferred for umbrellas because they are water-resistant and do not allow water to pass through easily. Both nylon and polyester have properties that make them ideal for protecting against rain, as they repel water and dry quickly after use.
- 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. Metals: Sodium, Bismuth, Silver, Iron, Copper. Non-metals: Nitrogen, Carbon, Chlorine. Metalloid: Silicon. Metals are elements that are generally shiny, malleable, ductile, and good conductors of heat and electricity. Sodium, bismuth, silver, iron, and copper all possess these metallic properties. Non-metals are elements that are typically poor conductors of electricity and heat, and they are generally not malleable or ductile. Nitrogen, carbon, and chlorine are non-metallic elements with these characteristics. Metalloids are elements that have properties intermediate between metals and non-metals. Silicon is classified as a metalloid because it has some properties of metals and some prop…
- 25. 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.
- 26. Current travels at the speed of 1/100th times the speed of light 0.0002 m/s.
- 27. 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.
- 28. Two features of Protista are that it includes unicellular and few simple multicellular eukaryotes with a membrane-bound nucleus and organelles. Another feature is that it includes plant-like protists such as algae, which can photosynthesize, and animal-like protists such as protozoans, which are heterotrophic and move using cilia, flagella, or pseudopodia. These organisms are primarily found in aquatic environments and represent a diverse group of organisms that do not fit neatly into other kingdoms.
- 29. Wool possesses several important characteristics that make it a valuable textile fiber. It is resistant to heat, water, wear and tear, which means it can withstand harsh conditions and frequent use without deteriorating quickly. Wool has excellent moisture-absorbing properties, allowing it to absorb perspiration while keeping the wearer comfortable. It is an outstanding insulator against cold, trapping warm air within its fibers to provide warmth during colder months. Additionally, wool does not wrinkle easily, maintaining its appearance and shape even after extended wear, which reduces the need for frequent ironing and makes wool garments practical for everyday use.
- 30. 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.
- 31. When the bottle is heated, the balloon expands because the air inside the bottle gets heated and expands. As the temperature of the air increases, the air molecules move faster and spread out, requiring more space. This increased pressure and volume of the air pushes against the walls of the balloon, causing it to stretch and expand outward. The balloon inflates as the heated air exerts more force on its flexible rubber surface.
- 32. Artificial ripening of fruit is an irreversible chemical change. During this process, the chemical composition of the fruit changes as the starches are converted into sugars and the fruit develops its characteristic color, flavor, and texture. Once the fruit has ripened through artificial means, it cannot be converted back to its unripe state, making it an irreversible change.
- 33. Atomic numbers and mass numbers are always whole numbers because they are based on counting discrete sub-atomic particles. The atomic number represents the number of protons in the nucleus of an atom. Since protons are indivisible particles that cannot be split into fractions, the number of protons must always be a whole number. There cannot exist a fraction of a proton in an atom; an atom either has a proton or it does not. Similarly, the mass number represents the total count of nucleons, which includes both protons and neutrons. Since both protons and neutrons are discrete particles that come in single units and cannot be divided, the total number of nucleons must also be a whole numbe…
- 34. Two merits of the Five Kingdom classification are as follows. First, this system of classification is more scientific and natural compared to earlier classification systems because it is based on multiple characteristics of organisms rather than just one or two features. It takes into account the fundamental differences between organisms at the cellular and molecular level. Second, this system of classification clearly indicates the cellular organization of organisms, their mode of nutrition, and the characteristics that reflect the early evolution of life on Earth. By organizing organisms into five kingdoms based on these criteria, it provides a better understanding of how different grou…
- 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 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.Light that hits a mirror gets ______A. TransmittedB. ReflectedC. AbsorbedD. Refracted[1]
2._______ is an example of a periodic changeA. EarthquakeB. Formation of rainbow in skyC. Occurrence of tides in seasD. Showering of rain[1]
3.Basis unit of life.A. CellB. ProtoplasmC. CelluloseD. Nucleus[1]
4.the outer most layer of an animal cell. Who am I?A. Cell wallB. NucleusC. Cell membraneD. Nuclear membrane[1]
5.________ is non-biodegradable material.A. PaperB. A plastic bottleC. Cotton clothD. Wool[1]
6.Which parts of the goat and sheep is used for manufacturing clothes?A. LegB. HandC. HairD. Head[1]
7.Write the binomial name ofA. Human beingB. Paddy[1]
8.The first man-made fibre is ________A. NylonB. PolyesterC. RayonD. Cotton[1]
9.Asexual reproduction in yeast isA. Spore formationB. FragmentationC. PollinationD. Budding[1]
10.Which of the following is correct?A. 1L=lccB. 1L= l0ccC. 1L= l00ccD. 1L= l000cc[1]
Part II — Fill in the Blanks 5 × 1 = 5
Fill in the blanks. (Answer all questions.)
11.______ 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]
12.Cell wall: plant cell:: centriole :_________[1]
13.Let us learn the characteristics of the subatomic particles through the following activity. Label the parts in the given diagram and answer the following. The positively charged particle is ________ The negatively charged particle is ________ ________ is neutral.[1]
14.In _______ equilibrium its centre of gravity remains at the same height when it is displaced.[1]
15.Take a leaf from any one of trees in your neighborhood. Place the leaf on a graph sheet and draw the outline of the leaf with a pencil. Remove the leaf. You can see the outline of the leaf on the graph sheet. Now, count the number of whole squares enclosed within the outline of the leaf. Take it to be M. Then, count the number of squares that are more than half. Take it as N. Next, count the number of squares which are half of a whole square. Note it to be P. Finally, count the number of squares that are less than half. Let it be Q. M = _______;N = _______; P = _______; Q = _______ Now, the approximate area of the leaf can be calculated using the following formula: Approximate area of the leaf = M +(\(\frac { 3 }{ 4 }\)) N+(\(\frac { 1 }{ 2 }\)) P+(\(\frac { 1 }{ 4 }\)) Q square cm Area of the leaf =________. This formula can be used to calculate the area of any irregularly shaped plane figures.[1]
Part III — True or False 5 × 1 = 5
Write True or False. (Answer all questions.)
16.Two different elements may have similar atoms.[1]
17.The fuse wire does not melts whenever there is overload in the wiring.[1]
18.Galilio accepted the Geo-centric model.[1]
19.An atom is electrically neutral.[1]
20.Degradable plastics break down into tiny pieces called microplastics.[1]
Part IV — Short Answer Questions 12 × 2 = 24
Answer briefly. (Answer all questions.)
21.Why lysosomes are known as scavengers of the cell?[2]
22.What is Tux Paint ?[2]
23.Name few insulators.[2]
24.“She moves at a constant speed in a constant direction”. Rephrase the same sentence in fewer words using concepts related to motion.[2]
25.Peeled and unpeeled banana does not look the same. Does that mean peeling banana is a chemical change?[2]
26.What are the main things in a nucleus?[2]
27.Which of these fabrics dries the fastest? The cotton cloth or the umbrella cloth?[2]
28.Tuberculosis is caused by the bacterium .[2]
29.Right and wrong application of plastics. Look at the list of eight plastic items. Decide which four plastic items are used for the right application and which four are used for the wrong application by filling in the chart below: Plastic items: straws, helmets, cutlery, thin carry bags, syringes, electrical wires,tea cups and blood bags[2]
30.What do you observe while the cotton cloth burns?[2]
31.How to close a document?[2]
32.Do you think that an individual cell is living? Explain your answer.[2]
Part V — Long Answer Questions 3 × 5 = 15
Answer in detail. (Answer all questions.)
33.With the help of Microsoft Photostory how will you create a video on a photostory?[5]
34.Define valency? What is the valency of the element with atomic number 8? What is the compound by the element with hydrogen.[5]
35.Take two pans, one wide and another narrow. Fill hot water in both to the same depth. Keep them in open. Observe after one to two hours. The pan that is wide has cooled more than the narrow one. That is more the surface area; the rate of evaporation is more. From this, can you guess why we unfurl the clothes while putting them to dry, rather than just drape them over the cloth line?[5]
🔑 Show Answer Key — Set 3
- 1. (b) Reflected
- 2. (a) Earthquake
- 3. (a) Cell
- 4. (c) Cell membrane
- 5. (d) Wool
- 6. (c) Hair
- 7. Binomial name (a) Human being – Homo sapiens (b) Paddy – Oryza sativa
- 8. (c) Rayon
- 9. (d) Budding
- 10. (d) 1L = 1000cc
- 11. Raincoat Resin codes polymer plant fibre silk
- 12. Animal cell.
- 13. Proton Electron Neutron
- 14. neutral
- 15. M = 50 N = 7 P = 4 Q = 4
- 16. True. Two different elements may have similar atoms because atoms of different elements can have the same number of electrons or similar electron configurations in their outer shells. However, what distinguishes one element from another is the number of protons in the nucleus of their atoms. For example, atoms of different elements may have similar sizes or similar chemical properties, but they differ in their atomic number, which is determined by the number of protons. Therefore, while atoms of different elements may appear similar in some ways, they are fundamentally different due to their different nuclear composition.
- 17. False. The fuse wire melts whenever there is overload in the wiring. A fuse is a safety device designed to protect electrical circuits from damage caused by excessive current. When the current flowing through the circuit exceeds the rated capacity of the fuse wire, the wire becomes very hot due to the heat effect of electric current and melts, breaking the circuit and stopping the flow of electricity. This prevents damage to appliances and reduces the risk of fire hazards in household wiring.
- 18. 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.
- 19. 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.
- 20. True.
- 21. Lysosomes are known as scavengers of the cell because they contain powerful digestive enzymes that break down and remove waste materials, damaged organelles, and dead cells. When a cell part becomes old or damaged, lysosomes engulf it and digest it completely, cleaning up the cell. This process of breaking down and removing cellular waste is similar to how scavengers clean up unwanted material, which is why lysosomes are called the scavengers of the cell. They play a crucial role in maintaining cell health and preventing the accumulation of harmful debris.
- 22. 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.
- 23. 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.
- 24. The sentence 'She moves at a constant speed in a constant direction' can be rephrased more concisely using the concept of velocity. In physics, velocity is a vector quantity that describes both the speed of an object and its direction of motion. Therefore, moving at a constant speed in a constant direction implies that the object's velocity is unchanging. Thus, a more succinct way to express this is: 'She moves with constant velocity.' This implies motion in a straight line without any change in the rate or path of movement.
- 25. No, peeling a banana is not a chemical change; it is a physical change. When we peel a banana, we are simply separating the skin from the fruit underneath. The composition of both the banana flesh and the peel remains unchanged. No new substances are formed, and no chemical bonds are broken or rearranged. The banana flesh still has the same chemical properties, taste, and nutritional composition whether it is covered by the peel or not. The change in appearance is only due to the removal of the outer covering, not due to any alteration in the chemical nature of the banana itself. Since the chemical composition and properties of the banana remain the same, peeling is classified as a physic…
- 26. 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.
- 27. 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.
- 28. 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.
- 29. Right application of plastics: Helmets are made from strong, rigid plastics that provide protection and durability needed for safety. Syringes are made from sterilizable plastics that are safe for medical use and can be easily disinfected. Electrical wires are insulated with plastics because they are excellent insulators and prevent electric shock. Blood bags are made from plastics that are sterile, safe for storing blood, and do not react with blood. Wrong application of plastics: Straws are single-use items made from plastics that contribute to pollution and are not necessary for daily function. Thin carry bags are made from non-biodegradable plastics that cause severe environmental pol…
- 30. When cotton cloth burns, it burns completely without melting. The burning process produces an odour similar to burning paper, which is characteristic of natural cellulose fibres. Cotton does not melt because it is a natural fibre made of cellulose, which decomposes at high temperatures rather than melting into a liquid form like synthetic fibres do.
- 31. 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.
- 32. Yes, an individual cell is living. Cells are the basic units of life and are considered the smallest living things. A single cell can perform all the functions of life, including metabolism, growth, reproduction, response to stimuli, and excretion. Even unicellular organisms like bacteria and amoeba consist of just one cell and are living things. Cells are found in plants, animals, and bacteria, and they exhibit all the characteristics that define living organisms.
- 33. Microsoft Photostory can be used to make videos using photos. First we have to upload the photos and then select music for the video. Step 1: Open the application of ‘Microsoft Photostory’. In that select ‘Begin A New Story’ and click on Next. Step 2: Click ‘Import Picture’ in the next screen. Now, the files in our computer will appear. Select Saved pictures for video. Step 3: Now we can input small text which is apt to the pictures. Then click on ‘Next’ and give animation to the videos. We can give audio effect also to these images. After finishing this click on ‘Next”. Step 4 : To provide background music, we can select a music file through “Select Music” and click on “Next”. Step 5: Ne…
- 34. Valency is defined as the combining capacity of an element, which represents the number of electrons an atom can lose, gain, or share when forming chemical bonds with other atoms. The valency determines how many atoms of another element a particular element can combine with. For the element with atomic number 8, which is oxygen, the valency is 2. Oxygen has 8 protons and typically 8 electrons arranged as 2, 6 in its electron shells. To achieve a stable electron configuration, oxygen needs to gain 2 electrons or share 2 electrons, giving it a valency of 2. When oxygen combines with hydrogen, which has a valency of 1, the compound formed is water with the chemical formula H₂O. In water, two…
- 35. Wet clothes dry faster when we unfurl or spread them out because the rate of evaporation depends directly on the surface area exposed to air. When we spread clothes wide and hang them separately, we increase the total surface area from which water can evaporate. The greater the surface area in contact with air, the more water molecules from the wet cloth can escape into the atmosphere as water vapor, and therefore the faster the evaporation occurs. In contrast, if we simply drape wet clothes over a clothesline without unfolding them, the clothes remain bunched up with a smaller exposed surface area, which results in slower evaporation and longer drying time. By unfolding and spreading the…