ISFO Science Practice Book Grade 8 PDF

Empowering children to become Global Olympiad Champions SCIENCE OLYMPIAD PRACTICE BOOK ADE GR 8 The Science Olympiad series is an initiative of Interna...

Empowering children to become Global Olympiad Champions SCIENCE OLYMPIAD PRACTICE BOOK ADE GR 8 The Science Olympiad series is an initiative of International Society for Olympiad (ISFO) International Society for Olympiad acknowledges the contribution of all its authors, content writers and designers in the creation of this book. Copyright ©International Society for Olympiad All rights are reserved with the publisher. No part of the work may be reproduced, stored in retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without the prior written permission of the publisher. Any errors or omissions are unintentional. We would be grateful for notification of corrections that should be incorporated in the future reprints. First Published - 2016 Revised Edition - 2017 Revised Edition - 2018 Revised Edition - 2019 Revised Edition - 2022 Published by International Society for Olympiad 193, Ganpati Enclave, Jharsa Road, Gurgaon (India) www.isfo.in Preface Our education system effectively provides an introduction to the concepts of Math and Science and helps us understand the underlying concepts. But in its overly generalized approach, which aims to enlighten and test all students of varying caliber and interests, it leaves the exploration of application of all these concepts completely on the students. This workbook is designed to enable students to explore Science effectively. Designed in accordance with the requirements of the Science Olympiads, the workbook is an efficient tool to achieve comprehensive success at the ISFO – Science Olympiad. The main aim of this workbook is to assist students in developing and improving their ability to solve problems. Each chapter of the book consists of 3 sets of questions. Section A (Scientific Reasoning) : This section is created to test the knowledge of scientific concepts and topics pertaining to the respective grades. Section B (Everyday Science) : This section deals with the application of the concept learnt. Section C (BrainBox) : Questions to prepare students with HOTS (Higher Order Thinking Skills), based on the syllabus provided. Logical Reasoning section is provided to equip students with verbal and non-verbal analysis and reasoning skills. Sample Test Papers and Answer keys have been provided to accelerate the learning process. Contents 1. Crop Production and Management 5 2. Microorganisms : Friends and Foes 10 3. Synthetic Fibres and Plastics 15 4. Coal and Petroleum 20 5. Combustion and Flame 25 6. Metal and Non-metal 30 7. The Cell 35 8. Reproduction and Endocrine System 40 9. Force, Pressure and Friction 45 10. Sound 50 11. Chemical Effects of Electricity and Natural Phenomenon 55 12. Light and Our Universe 60 13. Logical Reasoning 65 Answers 70 4 Chapter Crop Production and 1 Management ⇒ We need to adopt certain agricultural practices in order to provide food to our growing population day by day. Plants of the same kind grown and cultivated at one place on a large scale for food, clothing, medicines, cosmetics, dyes, etc. are called crops. In India, crops are categorised into two types on the basis of seasons; that is, Rabi and Kharif crops. The crop production practice involves a series of processes which are as follow : Preparation of soil by tilling and levelling Sowing of seeds into the prepared soil Adding manure and fertilisers for replenishment and enrichment of soil, ensuring healthy growth of crops Supplying of water to crops at appropriate intervals, called as irrigation Protecting crops from weeds by using weedicides Harvesting of crops by machines and their proper storage to protect them from harmful effects of pests and microorganisms Like plants, animals also provide us with a large variety of food items for which they are reared at homes or in farms. They are provided with proper food, shelter and care, which is called animal husbandary 5  SECTION - A : SCIENTIFIC REASONING 1. C  ontinuous growing of crops makes 6. W  hich of the following gases is evolved in the soil poorer and less-fertile. We can the process of anaerobic digestion of organic replenish soil by the following method. waste? a. Adopting crop rotation a. Oxygen gas b. Using weedicides b. Nitrogen gas c. Levelling c. Water gas d. Ploughing d. Biogas 2. Frequency of watering should be higher in 7. Which of the following represents an odd the summer season due to: combination? a. Increased evaporation from soil. a. Chilli, tomatoes and paddy b. Decreased evaporation from soil. b. Coffee, tea and rubber plant c. Decreased rainfall. c. Seed drills, hoe and wild bramble d. Increased wastage of water by plants d. Rice, maize and sorghum 3. It is important to make the soil loose 8. Growth and multiplication of microorganisms because it is better in: a. Removes insects from soil. a. Wet soil because it allows multiplication b. Allows the stem to be more erect. due to the presence of air. c. Holds more air and water. b. Dry soil because it allows multiplication d. Requires less manure. due to the absence of air and water. c. Tight soil because it allows 4. The precaution for preventing seeds from multiplication due to the presence of air insects can be taken by: and water. a. Sowing them properly. d. Loose soil because it allows multiplication b. Rejecting the unhealthy plants. due to the presence of air and water. c. Timely inspection of the store houses. 9. The different measures which help to d. Spraying chemicals beforehand. increase crop yield are: 5. The seeds selected for sowing should be a. Improving soil fertility by scientific methods and protection of plants from I. Clean and healthy pests and weeds. II. Disease resistant b. Following suitable agricultural practices III. Bigger in size and control of plant diseases. IV. Freshly stored c. Using good quality seeds and awareness a. I and II b. II and IV of new agricultural technology. c. Both a. and b. d. III and IV d. All of these 6 10. The role of fertilizer is to: b. It involves cutting and gathering of the a. Provide with specific nutrients required mature crops. by the soil/crop. c. It is done by mechanical harvesters or b. Cause rapid development of crops. combine. c. Get absorbed in the soil. d. Grains are harvested manually by hand picking. d. Provide the soil with economical agricultural practices. 14. Identify the traditional method(s) of irrigation from among the following list. 11. The seeds should be sown at a particular depth, because: I. Moat II. Chain pump III. Sprinkler system IV. Dhekli a. This will enable the farmer to check the seeds easily. a. I and II b. III and IV b. It prevents the loss of seeds. c. I, II and IV d. I, II and III c. It leads to better germination of seeds. 15. A  rrange the following in a proper d. It provides with abundant supply of sequence, representing the correct order water to the seeds. of production of cotton crop. I. Sowing of cotton seeds 12. A major disadvantage of using fertilisers is that: II. Manuring III. Ploughing the field a. They are made only by chemicals. IV. Preparation of the soil b. Their overuse may harm the soil. V. Sending crops to the cotton factory c. They are nutrient specific. VI. Irrigation d. Their frequency of use is limited VII. Harvesting 13. Which of the following statements is a. IV, II, III, I, VI, VII, V incorrect? b. IV, III, I, II, VI, VII, V a. Harvesting is done at the final stage of c. V, III, I, II, VI, VII, IV the agricultural task, wherein the fully grown plant needs cutting. d. IV, II, I, III, VI, VII, V SECTION - B : EVERYDAY SCIENCE 16. R  aghu is a farmer. By mistake, he sowed a. I is correct and II is the correct explanation wheat in kharif season. What will be the of I. effect of this mistake made by Raghu on b. I is incorrect and II is correct. the wheat crop and the soil? c. Both I and II are incorrect. I. Air in the soil space in which wheat is d. I is correct and II is the incorrect explanation of I. sown will reduce because of rainfall and waterlogging in kharif season. 17. Indian farmers are unhappy over the II. T his will not allow the germination of introduction of “Terminator Seed wheat seeds in the kharif season. Technology” because the seeds produced by this technology are expected to: 7  a. Give rise to sexually sterile plant. 19. Vinay wants to practice crop rotation in his b. Give rise to low-yielding plants despite field. Which of the following rabi and kharif the high quality. crops will replenish his field with nitrogen? c. Show poor germination. Rabi Crop Kharif Crop d. Give rise to the plants that are a. Maize, Paddy, Wheat, Pea, Mustard incapable of forming viable seeds. Soyabean 18. Akshat placed a few healthy seeds in three b. Wheat, Pea, Maize, Paddy, Soyabean pots A, B & C containing same type of Mustard soil. The soil in pot ‘A’ is mixed with green c. Barley, Paddy, Mustard, Soyabean, leaves, the soil in pot ‘B’ is mixed with old Wheat Gram cow dung while the soil in pot ‘C’ is mixed d. Barley, Maize, Mustard, Soyabean, Gram with chemical fertilizer. All the three pots Paddy were watered regularly and given proper 20. Now-a-day, every second person, in urban environment for plant growth. What area, talks about organic food. Grade 8 would Akshat observe after 10–15 days? students decided to produce organic food a. Lot of growth in pot ‘C’ with in schools garden. What should they do? replenishment of all nutrients. a. They should add urea in the soil before b. Lot of growth in pot ‘B’ with sowing seeds. replenishment of all nutrients. b. They should use manures and not c. Lot of growth in pot ‘A’ without fertilisers. replenishment of the nutrients. c. They should sprinkle pesticides and d. No growth in pot ‘A. weedicides for better production. d. Both a. and c. SECTION - C : BRAINBOX 21. Which of the following statements is/are 22. Match list I with list II and select the correct, regarding the storage of food? correct answer using the codes given I. The safety measure used for the below the lists: storage of grains since a long time is that the grains should be properly List I List II dried in the sun to reduce moisture a. Barley 1. Hot and dry climate because moisture increases the growth with poor soil of organisms. b. Rice 2. Cool climate with II. At home, we could use dried Neem poorer soil leaves to store the food grains. c. Millets 3. Warm and moist III. For storing large quantities of grains in climates with high big godowns, specific chemical altitude treatments are required to protect d. Tea 4. Hot and moist them from pests and microorganisms. climate with rich soil a. I and II b. I, II and III c. Only II d. II and III 8  A B C D 24. Crop production and management is a. 2 1 4 3 necessary because: b. 3 4 1 2 I. All animals including human beings are c. 2 4 1 3 dependent on plants for their food. d. 3 2 4 1 II. As our population increases day by day, requirement of food also 23. Which of the following statements are increases. correct about the plough? III. Agriculture is the only source of I. The plough contains a strong triangular livelihood for many people. iron strip called a ploughshare Mark the correct option. II. The main part of the plough is a long log a. I and II b. I and III of wood which is called a ploughshaft. c. I, II and III d. II and III III. In earlier days, ploughs were drawn by working animals such as horses or 25. Manures are considered better than cattle, but in modern times ploughs fertilisers, because they: are drawn by tractors. I. Provide humus to the soil. a. I and II II. Are slowly absorbed by the plants. b. I and III III. Make the soil porous which allows c. I, II and III exchange of gases in the soil. d. II and III IV. Decrease the number of microbes. a. I and II b. II and IV c. I, II and III d. III and IV Darken your choice with HB pencil 1. a b c d 8. a b c d 15. a b c d 22. a b c d 2. a b c d 9. a b c d 16. a b c d 23. a b c d 3. a b c d 10. a b c d 17. a b c d 24. a b c d 4. a b c d 11. a b c d 18. a b c d 25. a b c d 5. a b c d 12. a b c d 19. a b c d 6. a b c d 13. a b c d 20. a b c d 7. a b c d 14. a b c d 21. a b c d 9 Chapter Microorganisms: 2 Friends and Foes Microorganisms are so small that we cannot see them with unaided eyes. They are found in air, water and inside the bodies of plants and animals. They can live in all kinds of environments ranging from very cold climate to hot springs and deserts to marshy areas. They may be unicellular or multicellular. Microorganisms are broadly classified into four major groups, namely, bacteria, fungi, protozoa and some algae. Viruses are quite different from other microorganisms. They are non-living outside the host cell but as soon as they enters the host cell they become living by showing all characteristics of living organisms. Microorganisms are very useful to us; some are used in the commercial production of medicines and alcohol while some are eco-friendly and help in cleaning our environment. Some microorganisms are harmful as they cause serious diseases in plants and animals. Some of the microorganisms grow on our food stuff and cause food poisoning. Some microorganisms reside in root nodules of leguminous plants and fix and convert the atmospheric nitrogen into nitrates and increase soil fertility. 10  SECTION - A : SCIENTIFIC REASONING 1. My mother asked me to cover my mouth 6. Bacteria present in the root nodules of and nose while sneezing as I was suffering leguminous plants which fix atmospheric from a : nitrogen to be used by the plant is a. Hereditary disease a. Rhizobium b. Nostoc b. Sexually transmitted disease c. Azospirillum d. Acetobacter c. Communicable disease 7. Tina bought a packet of pasteurized milk d. Congenital disease and drank without boiling it because it 2. Which of the following is a simplest a. Tasted sweet protozoan? b. Was free from microorganisms a. Amoeba b. Paramecium c. Was rich in minerals and vitamins c. Euglena d. Plasmodium d. Was proteinaceous in nature 3. Which of the following statements is 8. Once a person is infected with smallpox, correct about plant diseases? he does not suffer from it again as his body contains: a. Serious plant diseases caused by fungi a. Antigens b. Antibodies can wipe out the whole crop. c. Anticoagulants d. Antibiotics b. Plants are being developed through biotechnology and hybridization to 9. Which of the X have resistance against diseases. following is correct c. Plant diseases like rust, smut and wilt about the part are caused by fungi. labelled as X in the d. All of these given diagram? I. It is meant for feeding. 4. X is a medicine which is made with the II. It is meant for locomotion. help of microorganisms mainly fungi and bacteria and used in killing or stopping III. It is meant for food preparation. the growth of the disease-causing a. I and II b. II and III microorganisms. Here X can be: c. Only II d. Only III a. Vaccines b. Antibiotics 10. Leptothrix is an example of iron bacteria. c. Antipyretic drugs d. Analgesic Which of the following statements best fits the iron bacteria? 5. Statins used as blood cholesterol lowering agents are produced by a microbe called: a. They oxidise ferrous compounds to ferric oxide. a. Bacillus thuringiensis b. They are responsible for the preservation of b. Anabaena affinis iron-rich artefacts in archaeological material. c. Sesbania drummondii c. They cause rusting of iron. d. Monascus purpureus d. They cause iron to be deposited in the liver of animals. 11 11. There are more anti-bacterial drugs than a. 20 minutes b. 30 minutes anti-viral drugs because: c. 40 minutes d. 59 minutes a. Virus is smaller than bacteria. 14. Read the given correlation and complete it. b. Viral diseases are intracellular. c. Bacterial diseases are intracellular. Heat treatment : : Sterilisation : : d. Drugs can penetrate bacteria more Vaccination : P effectively. What is ‘P’ here? 12. Study the given pictures of organisms and a. Pasteurisation b. Immunisation choose the incorrect statement regarding c. Fertilization d. Inoculation these. 15. Which of the following statements is/are incorrect about microorganisms? I. Microorganisms are found everywhere in all kinds of environment. X Y II. Microorganisms can withstand high a. Organism ‘X’ is a unicellular green alga. and low temperatures. b. Organism ‘Y’ is a parasitic protozoan. III. Microorganisms have high degree of c. Organism ‘Y’ causes diseases in humans. adaptability. d. Both the organisms cannot synthesize IV. To tolerate unfavourable conditions, their own food. microorganisms’ cells get covered with a hard outer covering called cysts. 13. A bacterium undergoes a binary fission every minute. This bacterium can fill up a a. I and II b. II and III jar in 1 hour. How much time it would take c. I, II, III and IV d. None of these to fill the jar exactly half? SECTION - B : EVERYDAY SCIENCE 16. Riya had a severe stomach ache last night. 17. Rahul stays at a place where water keeps She had been vomiting all night. Doctor stagnating, allowing mosquitoes to breed. said that it had happened due to food He is in danger of contracting: poisoning a. Hepatitis B b. Typhoid a. Food poisoning could be due to the c. Malaria d. Tuberculosis consumption of food spoilt by some microorganisms. 18. Riya is doing an activity in a biological lab. b. Microorganisms that grow on our food She and her team mates allowed growth sometimes produce toxic substances of yeast on natural sugars present in grains which cause food poisoning. like barley, wheat, rice, crushed fruit juices. The result of this activity would be: c. Toxic substances make the food poisonous, causing serious illness and even death. a. Formation of beer d. Both a. and c. b. Formation of wine 12  c. Formation of cider 20. Which of the following is correct regarding d. All of these the application of biopesticides? 19. Which of the following represents an a. Bacillus thuringiensis is a bacterium incorrect match? that kills insect. b. Trichoderma, a fungus, controls many Human Causative Mode of pathogenic fungi present in the soil. Disease Micro- Transmission organism c. Certain bacteria and fungi are being used to control certain weeds and a. Tuberculosis Virus Air diseases in crop plants. b. Polio Virus Air/water d. All of these c. Malaria Protozoa Mosquito d. Typhoid Bacteria Water SECTION - C : BRAINBOX 21. Virus is a connective link between the I. Actinomyces II. Bacillus living and the non-living because III. Lactobacillus IV. E. coli I. The reason for their being non-living is V. Nitrobacter that they neither grow nor reproduce once outside the host cell. a. I and III b. II and IV II. They can be considered living as they c. I, II and III d. III and V multiply very fast and grow when they 24. Which of the are inside the host cell. following is correct about the organism GREEN layer on a. Only I b. Only II pond surface c. Both I and II d. None of these shown in the given image? 22. Match the following and choose the I. These are a very large and diverse correct option for this. group of simple, typically heterotrophic Column – I Column – II organisms, ranging from unicellular to multicellular forms. i. Citrus canker a. Fungi II. Most of them photosynthesize like ii. Rust of wheat b. Virus plants. iii. Insect mosaic of okra c. Bacteria III.  They reproduce either by asexual cell iv. Chicken pox division or by sexual reproduction. a. i-c, ii-a, iii-b, iv-b b. i-a, ii-b, iii-b, iv-c IV. All of these organisms have photosynthetic machinery ultimately c. i-c, ii-b, iii-a, iv-b d. i-a, ii-d, iii-c, iv-b derived from cyanobacteria and so they 23. Observe the cell are able to produce a gas as a walls shown in the by-product of photosynthesis. figure. Here figure I a. I and II b. I and III represents c. II, III and IV d. II and IV I II 13 25. Study the given diagram of bacteria P, Q and R. Identify these bacteria and find the correct match regarding diseases caused by these bacteria. P Q R P Q R a. Lactobacillus - Salmonella typhi - Streptococcus - a friendly bacteria causes Typhoid fever. causes throat trofosis b. Streptococcus - Lactobacillus - Salmonella typhi a disease causing organism a friendly bacteria - causes tuberculosis c. Streptococcus - Lactobacillus - Pseudomonas - a disease causing organism a friendly bacteria a friendly bacteria d Lactobacillus - Salmonella typhi - caus- Streptococcus- a a disease causing bacteria es many disease friendly bacteria Darken your choice with HB pencil 1. a b c d 8. a b c d 15. a b c d 22. a b c d 2. a b c d 9. a b c d 16. a b c d 23. a b c d 3. a b c d 10. a b c d 17. a b c d 24. a b c d 4. a b c d 11. a b c d 18. a b c d 25. a b c d 5. a b c d 12. a b c d 19. a b c d 6. a b c d 13. a b c d 20. a b c d 7. a b c d 14. a b c d 21. a b c d 14  Chapter Synthetic Fibres and 3 Plastics ⇒ Fibres are used for making a large variety of household articles Natural fibres like cotton, wool, silk, etc., are obtained from plants and synthetic fibres are made by human beings by chemical processing of petrochemicals. Like natural fibres, synthetic fibres and plastics are made of very large units called polymers and polymers are made of many smaller units. Synthetic fibres are used for making many household articles like rope, bucket, container, furniture, etc. They are also used in aircrafts, ships, spacecrafts, healthcare, etc. Different fibres have different strength, nature of burning, water absorbing capacity, cost, durability, etc. Synthetic fibres are of different types depending upon the chemical used in their manufacturing. They are nylon, rayon, polyester and acrylic. Plastics find extensive use in the healthcare industry like for packaging of tablets, for making thread used for stitching wounds, syringes, etc. Plastic takes several years to decompose. It is not environment friendly and causes environmental pollution, and so we should avoid using plastics as far as possible. 15  SECTION - A : SCIENTIFIC REASONING 1. X is a synthetic fibre made of a chemical a. The strength of carbon-sulphur bonds. called terephthalic acid. It is used for b. The strength of carbon-fluorine bonds. clothing, sheets, ropes, sails, etc. c. The strength of carbon bonds. Here X is: d. None of these a. Rayon b. Terelene 7. Polymer which is also known as teflon is: c. Nylon d. Acrylic a. Bakelite 2. Which of the following statements is b. Polythene correct about acrylic? c. Polytetrafluoroethylene a. It appears to resemble wool. d. Buna-S b. It is a synthetic fibre. 8. Nylon-66 is made from hexamethylene c. Woollen clothes made from acrylic tetramine (having six methyl group) and: are relatively cheaper than the clothes made from naturally obtained wool. a. Sulphurous acid with six atoms of various elements. d. All of these b. Adipic acid, a six carbon chain fatty acid. 3. Polyester is made of repeated units of c. Sulphur hexafluoride with six fluorine chemical called: atoms. a. Ether b. Ester d. Cobalt hexamine cation with six c. Acid d. Alcohol ammonia ligands. 4. Name two plastics which get deformed 9. Which of the following holds true for easily on heating and can be bent easily. rayon fiber? I. Rayon is synthesized from wood pulp. a. Elastomers and monomers II. Rayon resembles silk. So, it is also b. Polythene and PVC known as artificial silk. c. Thermoplastics and thermosetting III. Rayon can be dyed in different colours. plastics IV. Rayon is cheaper compared to silk. d. None of these a. I and II 5. Orlon is a: b. II, III and IV a. Polymer of vinyl cyanide c. I, II, III and IV b. Polymer of vinyl chloride d. None of these c. Polymer of chloroprene 10. Why melamine is used in making floor tiles? d. Polymer of ethyl chloride I. Melamine is a versatile material. 6. The synthetic polymer used for the coating II. It resists fire and can tolerate heat of non-stick cookware is a non-reactive better than other plastics. polymer. a. Both I and II b. Only I This is because of: c. Only II d. None of them 16 11. What are the factors that differentiate the 13. Match column A with B and choose suitable different types of fibres? option for this. I. Strength Column ‘A’ Column ‘B’ II. Water absorbing capacity i. Jute A. First synthetic fibre III. Nature of burning ii. Rayon B. Natural fibre IV. Cost iii. Nylon C. Polymer V. Durability iv. Repetition of D. Terylene a. I,II, III and IV small units b. II, III and IV v. Polyester E. Wood-pulp c. I,II, III, IV and V a. i- A, ii-E, iii-B, iv-C, v-D d. III and V b. i- B, ii-E, iii-A, iv-C, v-D 12. Why should we wear cotton clothes in c. i- C, ii-A, iii-B, iv-E, v-D summer? d. i- A, ii-E, iii-B, iv-D, v-C a. Cotton allows better air circulation, 14. You have to take extra care to iron synthetic which helps in absorbing and clothes because removing body moisture caused by sweat. a. They take long time to give a smooth look. b. Cotton is light in weight and is of light colour unless it is dyed. The light b. They got damaged at high temperature. colour of the cotton cloth helps the c. They need more water for ironing. light to pass through instead of being d. They are wrinkle free. absorbed and hence we do not feel the much heat. 15. Which of the following groups contains all synthetic substances? c. Cotton helps in bringing down the severity of any allergic reaction and is a. Nylon, Terylene, Wool perfect for those who have sensitive b. Cotton, Polycot, Rayon skin. c. Acrylic, Bakelite, Polythene d. All of these d. Silk, Wool, Acrylic SECTION - B : EVERYDAY SCIENCE 16. Uniforms of firemen are made up of 17. Plastic containers are preferred over iron melamine because: containers for storing food because plastic is I. Melamine resists fire and can tolerate I. Non-reactive heat better than other plastics. II. Durable II. Melamine is a good conductor of heat. III. Cheap and light in weight III. Melamine allows air to pass through it. IV. Corrosion resistant a. I and II b. II and III a. I and II b. II and III c. Only I d. None of these c. III and IV d. All of these 17 18. Why should we avoid clothes made of c. Nylon and polyester melt on burning. synthetic fibres in hot and humid weather? d. All of these I. Synthetic fibres catch fire very easily. 20. The disadvantages of using synthetic fibres II. Synthetic fibres may cause rashes, are – skin allergies and body odour as they tend to trap moisture. I. They are cheap and affordable. III. Synthetic fibres stick to the body. II. They are wrinkle free and thus, do not need ironing. IV. Synthetic fibres do not absorb sweat. III. They do not need maintenance like a. I , II and III b. II, III and IV natural fibres. c. Only II d. None of them IV. They melt easily and are prone to heat 19. Zoei took few synthetic and natural fibres damage. to study the effect of their burning. She V. They dry quickly and do not shrink. took nylon, wool, cotton, silk threads and VI. They are more elastic as compared to polyester and burnt them one by one. natural fibres. Choose the suitable option predicting the a. Only II observation of her experiment. b. Only IV a. Cotton and wool burn to form a residue. c. Only V b. Wool and silk burnt with the smell of d. Both IV and VI burning hair. SECTION - C : BRAINBOX 21. Preweighed pieces of cloth of Here X could be nylon, cotton, silk and wool of equal a. Petrol measurements are taken and soaked in a beaker filled with water. After a few b. Petroleum minutes, the cloth pieces were taken out c. Diesel of the beaker and weighed again. d. Coal tar Which of the following options places them 23. Observe the diagram shown below and in the correct order of their final weights? choose correct option for this. a. Nylon > cotton > silk > wool b. Wool > cotton > silk > nylon c. Wool > silk > cotton > nylon P d. Cotton > wool > silk > nylon 22. X is a source of synthetic polymers. It is a mixture of a number of carbon compounds which can be separated by the process of fractional distillation. Q 18  I. F igure P shows the structure of a 24. A student studied about the materials that monomer while figure Q shows the are used for making plugs and switches. structure of a polymer. P → A thermosetting which is used for II. Small boxes in the above structures making plugs and switches. represent monomers which are joined Q → A thermoplastic used as an insulation to give a polymer. for electric wires. III. Figure P shows the structure of a linear R → A thermoplastic which can be rolled polymer while Q shows the structure of into sheets. a cross-linked polymer. What are P, Q and R? a. I and II P Q R b. I and III a. PVC Polythene Bakelite c. II and III b. Polyethylene PVC Bakelite d. All of these c. Bakelite Melamine Teflon d. PVC Melamine Teflon 25. Observe the classification shown below and choose the suitable options for P, Q, R and S. Plastics and Fibres Plastics Fibres P Q R S Bakelite, Polyvinyl chloride, Silk, Cellulose, Melamine Polystyrene wool cotton P Q R S a. Thermosetting Thermoplastics Animal fibres Plant fibres b. Thermoplastics Thermosetting Plant fibres Animal fibres c. Non-biodegradable Biodegradable Animal fibres Rayon d. Biodegradable Non-biodegradable Plant fibres Animal fibres Darken your choice with HB pencil 1. a b c d 8. a b c d 15. a b c d 22. a b c d 2. a b c d 9. a b c d 16. a b c d 23. a b c d 3. a b c d 10. a b c d 17. a b c d 24. a b c d 4. a b c d 11. a b c d 18. a b c d 25. a b c d 5. a b c d 12. a b c d 19. a b c d 6. a b c d 13. a b c d 20. a b c d 7. a b c d 14. a b c d 21. a b c d 19 Chapter Coal and Petroleum 4 ⇒ Natural resources can be broadly classified into inexhaustible natural resources and exhaustible natural resources. Coal, petroleum and natural gas are exhaustible natural resources. Coal, petroleum and natural gas are called fossil fuels because they are formed from dead remains of living organisms. Coke, coal tar and coal gas are the products of coal. Coke is an almost pure form of carbon. Coal tar has an unpleasant smell and is mixture of about 200 substances. Petrol and diesel are obtained from a natural resource called petroleum. Petroleum gas, petrol, diesel, kerosene, paraffin wax and lubricating oil are obtained by the refining of petroleum. We should make wise and judicious use of exhaustible resources. 20  SECTION - A : SCIENTIFIC REASONING 1. The buried dead plants get converted to 6. Gross and net calorific values of a fuel will _______ due to high temperature and be the same: pressure underneath the Earth. a. Under no circumstances. a. Metal b. Coal b. If its carbon content is very low. c. Bacteria d. Rocks c. If its ash content is zero. 2. Which of the following happens in d. If its hydrogen compound content is zero. carbonisation? 7. Higher percentage of ash in coal meant for a. Carbon gets liberated into nature. the production of metallurgical grade coke: b. Dead vegetation is converted to coal. a. Decreases the hardness of coke. c. Carbon is formed from nature. d. Carbon is formed from coal. b. Decreases the abrasion resistance of coke. c. Causes brittleness in steel. 3. The dead aquatic organisms that were buried under the sand and clay of the sea d. None of these bed, were converted to petroleum owing 8. Which of the following is not a by-product to _________. recovered in a high temperature coal a. High pressure carbonisation plant? b. High temperature a. Pitch-creosote mixture (PCM) c. Absence of air b. Benzol d. All of these c. Naphthalene 4. Choose the correct statement from the d. Ethylene following 9. A coal with high ash content is undesirable, as: a. It is difficult to transport natural gas through pipes. a. The ash in molten condition gets b. The disadvantage of natural gas is that absorbed in the pores of the refractory it cannot be used directly for burning in lining of the furnace and causes its homes. spalling due to different co-efficient of expansion/contraction of the refractory c. Natural gas is stored under high and the ash. pressure as compressed natural gas. b. It is abrasive to the coal pulveriser (e.g. d. Natural gas cannot be used for power ball mill) and the combustion chamber. generation. c. The ash retains the sulphur and 5. Which of the following is known as chief phosphorus and thus affects the quality antiknock agent for automotive gasoline? of products in a metallurgical furnace; a. Tetraethyl lead apart from increasing the slag volume, b. Tetramethyl lead It may fuse and stick to the boiler tubes, thereby reducing the heat transfer. c. Tetraethylene lead d. Tetrapropyl lead d. All of these 21 10. The temperature at which plastic layer 13. Petroleum is called black gold because: formation takes place during carbonisation I. Of its appearance as black oily liquid. of coal varies from ________ °C. II. Of its great commercial importance. a. 100 to 150 b. 550 to 650 a. Only I b. Only II c. 350 to 450 d. 700 to 850 c. Both I and II d. None of these 11. A fuel containing carbon and carbon 14. Which of the following shows the correct monoxide (but containing no hydrogen or usage of petroleum products? its compounds) is burnt in pure oxygen at a constant pressure. Its gross calorific value a. Coke is used in the manufacture of steel as compared to net calorific value will be and in the extraction of many metals. a. Less b. Coal tar is used for metalling the roads. b. Same c. Coal gas is used as a fuel in many industries situated near the coal c. More processing plants. d. Data insufficient; can’t be predicted d. All of these 12. The petroleum product used as a solvent 15. Which of the following is the feature of for drycleaning is a good quality coal? a. Kerosene a. Low fusion point of ash b. Petrol b. High ash content c. Diesel c. High sulphur d. Paraffin d. None of these SECTION - B : EVERYDAY SCIENCE 16. Coal tar can be used as a starting material 18. Coke is a fuel with few impurities and light for the manufacturing of : carbon content. Which of the following is a. Drugs not a use of coke? b. Cookwares a. It is used as a reducing agent. c. Photographic materials b. It is used in the manufacture of steel. d. All of these c. It is used in the manufacture of coal gas. d. It is used in the manufacture of 17. Match Column I with Column II and find producer gas. the incorrect match. 19. Choose the incorrect statement. Column I Column II a. Oxygen in the air is an exhaustible a. Black Gold Petroleum natural resource. b. Paraffin wax Vaseline b. Wildlife is an exhaustible natural resource. c. Bitumen Road surfacing c. CNG is a less polluting fuel than petrol d. Coke A natural gas and diesel. 22  d. Under high temperature and pressure, b. We should use natural gas as a dead plants get slowly converted to coal. substitute. 20. Petroleum is a non-renewable source of c. Alternative sources of energy such energy. Which of the following steps are as solar, wind and biomass should be suggested for the judicious fuels? preferred. a. We should use fossil fuels when d. All of these necessary. SECTION - C : BRAINBOX 21. Study the given diagram of destructive 23. When air is passed through red hot coke, distillation of coal. a gaseous fuel is produced. Which of the following is correct about the fuel? C A Name of the fuel Composition a. Natural gas H2 + CO b. Producer gas N2 + CO B c. Water gas CO + H2 Identify the useful products obtained. d. Biogas CH4 + O2 A B C a. Coal gas Coal tar Coke 24. Fill in the blanks and find P, Q, R & S b. Coal gas Coke Coal “The low process of conversion of dead vegetation into coal is called P. Coal c. Coal gas Coal tar Impure coal and petroleum are formed from the dead d. CO2 Coal tar Coal remains of organisms and are known as Q. The black thick liquid with unpleasant 22. Study the given diagram showing smell is known as R. The process petroleum and natural gas deposits. of separating various constituents of petroleum is known as S. Rocks What are P, Q, R & S? P Oil a. P – Coal, Q – Fossil fuels, R – Coal gas, Rock Water S – Coal tar Which of the following is a correct b. P – Coal, Q – Fossil fuels, R – Coal tar, statement about the component P? S – Coal gas a. It is made of methane gas. c. P – Carbonisation, Q – Fossil fuels, R – Coal tar, S – Refining b. It is a clean and non-polluting fuel. d. P – Carbonisation, Q – Fossil fuels, c. It is a gas and stored under high pressure. R – Coal gas, S – Refining d. All are correct 23 25. In fractionating column, various fractions are obtained at various heights of the column. As the vapour reach at a height where temperature is equal to or just below the boiling point of that fraction, it will: a. Condense to form a liquid. b. Remain in gaseous state. c. Condense to form a solid. d. Escape from the column. Darken your choice with HB pencil 1. a b c d 8. a b c d 15. a b c d 22. a b c d 2. a b c d 9. a b c d 16. a b c d 23. a b c d 3. a b c d 10. a b c d 17. a b c d 24. a b c d 4. a b c d 11. a b c d 18. a b c d 25. a b c d 5. a b c d 12. a b c d 19. a b c d 6. a b c d 13. a b c d 20. a b c d 7. a b c d 14. a b c d 21. a b c d 24 Chapter Combustion and 5 Flame The chemical process in which a substance reacts with oxygen to give off heat is called combustion. The substance which undergoes combustion is called combustible substance or fuel. Fuel may me solid, liquid or gas. The lowest temperature at which a substance catches fire is called its ignition temperature. Substances which have very low ignition temperature and can easily catch fire with a flame are called inflammable substances; like petrol, LPG, etc. The three essential requirements for producing fire are fuel, air and heat. Fire can be controlled by removing one or more of these requirements. There are three types of combustions, namely, rapid combustion, spontaneous combustion and explosion. An ideal fuel is cheap, readily combustible, readily available, having high calorific value and easy to transport. Incomplete combustion of fuel releases carbon monoxide gas which is poisonous and harmful for our atmosphere. 25  SECTION - A : SCIENTIFIC REASONING 1. Flames are formed when the substance: 7. Low temperature carbonisation: a. Melts during burning. a. Is mainly for producing smokeless b. Vaporises during burning. domestic coke. c. Boils during burning. b. Produces higher quantity of gas compared d. All of these to high temperature carbonisation. c. Is meant for the production of 2. The heat of combustion of a fuel: ‘metallurgical coke. a. Is equal to the heat of formation. d. None of these b. Is always negative. 8. Which of the following is a false statement? c. Can’t be known without calculating it. d. Is always positive. a. Ideal fuel is cheap and easily available. b. Complete combustion of a fuel gives 3. Main constituents of BTX are carbon monoxide gas. a. Anthracene and phenol c. Inflammable substances have very low b. Tar and creosote ignition temperature. c. Benzene, toluene and xylene d. Combustion produces heat and light. d. Ammonia and phenol 9. Which is not the example of combustion? 4. Higher efficiency in the combustion of a. Burning of sodium in air. solid fuel cannot be achieved by b. Spontaneous reaction of coal dust in a. Keeping the gas exhaust temperature coal mines. very high. c. Reaction of food in our body. b. Adopting efficient-fuel firing technique d. Reaction occurring in the sun. and equipment. c. Proper fuel preparation. 10. Match the column ‘I’ with column ‘II’: d. Supplying correct quantity of Column I Column II combustion air. 1. CNG A. Combustible 5. During combustion of gaseous fuels, substance deficiency of air: 2. LPG B. Inflammable a. Does not affect the flame length. substance b. Tends to shorten the flame. 3. Wood, Charcoal C. Cleaner fuel c. Increases the flame temperature. 4. Alcohol, Petrol D. Liquid fuel d. Lengthens the flame. a. 1-C, 2-D, 3-A, 4-B 6. Presence of _______ in a dry gaseous fuel does not contribute to its calorific value. b. 1-C, 2-D, 3-B, 4-A c. 1-D, 2-C, 3-B, 4-A a. Sulphur b. Oxygen d. 1-C, 2-B, 3-A, 4-D c. Carbon d. Hydrogen 26 11. The correct order of the combustion of a. Yield of carbonised products. the following is: b. Friability and oxygen content. a. Methane > Ethane > Propane > Butane c. Caking index. b. Ethane > Methane > Butane > Propane d. Calorific value. c. Butane > Propane > Ethane > Methane 14. Combustion of pulverised coal as d. None of these compared to that of lump coal: 12. Ratio of primary air to secondary air increases a. Can be done with less excess air. with increase in the rank of coal, because the b. Develops a non-luminous flame. a. Ratio of fixed carbon to volatile matter c. Provides a lower rate of heat release. increases. d. Develops a low temperature flame. b. Calorific value of the coal increases. 15. The head of a safety match contains c. Oxygen content progressively decreases. d. High rank coals have higher amount of a. Antimony trisulphide and potassium volatile matter. chlorate. b. Antimony chloride and potassium sulphide. 13. Improper storage condition results in the weathering of coal and spontaneous c. Antimony carbonate. combustion, which increases its d. Potassium sulphide SECTION - B : EVERYDAY SCIENCE 16. Liquid and gaseous fuels have more 18. Aditi, accidently puts an inverted glass advantages over solid fuels. Which of the over a lighted candle. following is not a correct statement in She observed that the candle blows off in regard with their advantages? few seconds. Why does this happen? a. Calorific value of liquid and gaseous fuels a. The candle keeps burning as long as air is higher than that of the solid fuels. is present in the glass and then it goes b. Liquids and gaseous fuels have higher off. ignition temperature than the solid fuels. b. The ignition temperature of the candle c. Liquids and gaseous fuels are easier to becomes low due to glass cover hence store since solid fuels occupy lot of space. it goes off. d. Liquids and gaseous fuels burn c. The candle keeps burning as long as completely, leaving no residue. the complete wax melts away and then 17. Riya’s mother was cooking potato curry on goes off. a Chulha. She observed that the copper d. O2 is produced when candle burns vessel was getting blackened from outside. which helps the candle to burn initially. It may be due to _______. a. Proper combustion of fuel. 19. Global warming leads to a rise in sea level which causes floods in the coastal b. Improper cooking of potato curry. areas. One of the main reasons of global c. Improper combustion of fuel. warming is _______. d. Burning of copper vessels. 27  a. Combustion of fuels releases SO2 which 20. Read the given statements and choose the increases the temperature. incorrect one. b. Combustion of fuels releases CO which a. Water is a very good fire extinguisher decreases the temperature. as it cools down the fuels such as wood c. Combustion of fuels releases unburned below its ignition temperature. carbon particles which causes decrease b. Water is a very good fire extinguisher for in temperature. burning oils and electrical equipment. d. Combustion of fuels releases CO2 which c. Sand and soil may act as a good fire causes increase in temperature. extinguisher for burning oils. d. Both a and c SECTION - C : BRAINBOX 21. Fuel gases containing hydrocarbons (i.e. 23. When a frying pan containing cooking oil coke oven gas) are not preheated before is kept for long on a burning stove then burning, mainly because cooking oil catches fire, because: a. This reduces its calorific value a. Its temperature is lower than its tremendously. ignition temperature. b. The hydrocarbons crack thereby b. Its temperature reaches to its ignition choking and fouling the heat transfer temperature. surface by carbon soot. c. Its temperature is lower than the c. This reduces its flame temperature critical temperature. tremendously. d. Its temperature is higher than the d. There are chances of explosion during critical temperature. preheating. 24. Match the items of column I with the 22. Calorific values of some fuels are : items of column II Fuels Calorific Value (kj/kg) Column I Column II Diesel 45000 p. Oxides of S and N i) Fire extinguisher q. CNG ii) Incomplete CNG 50000 combustion of LPG 55000 coal r. O2 iii) Very low ignition Coal 25000 – 33000 temperature Arrange these fuels in correct order of s. Inflammable iv) Acid rain substance their efficiency. t. CO2 v) Necessary for a. LPG > CNG > Diesel > Coal combustion b. Coal > Diesel > LPG > CNG u. CO vi) Fuel for c. Diesel > CNG > Coal > LPG automobiles d. CNG > LPG > Diesel > Coal 28  Choose the correct option – IV. Increased concentration of N2 in air is a. p – iv, q – v, r – vi, s – iii, t – ii, u – i believed to cause global warming. b. p – iv, q – vi, r – v, s – iii, t – i, u – ii V. Alcohol, CNG and LPG are inflammable substances. c. p – iii, q – v, r – iv, s – ii, t – vI, u – i Choose the incorrect statement. d. p – ii, q – iii, r – iv, s – v, t – vi, u – i a. I, II and III 25. Read the given statements about fuels. b. III, IV and V I. The substances which vaporise during c. I, II, III and V burning, giving flame. d. I, III and V II. Middle zone is the hottest zone of a flame. III. Greater the calorific value, better is the fuel. Darken your choice with HB pencil 1. a b c d 8. a b c d 15. a b c d 22. a b c d 2. a b c d 9. a b c d 16. a b c d 23. a b c d 3. a b c d 10. a b c d 17. a b c d 24. a b c d 4. a b c d 11. a b c d 18. a b c d 25. a b c d 5. a b c d 12. a b c d 19. a b c d 6. a b c d 13. a b c d 20. a b c d 7. a b c d 14. a b c d 21. a b c d 29 Chapter Metal and Non-metal 6 ⇒ There are 92 elements occurring naturally, out of which 70 are metals and about 22 are non-metals. Some elements show properties of both metals and non-metals; they are called metalloids. Metals are solid, hard, malleable and ductile. Metals have high melting and boiling points and are good conductors of heat and electricity Non-metals may be solid, liquid or gas, and are not malleable and ductile. Non-metals have low melting and boiling points and are poor conductors of heat and electricity Metals are sonorous. Metals react with acids to produce metal salts and hydrogen gas; generally non-metals do not react with acids. Some of the metals react with bases to produce hydrogen gas. In an aqueous solution, less reactive metals are displaced by more reactive metals. Metals react with ester to produce metal hydroxides and hydrogen gas. Metals like gold, silver, platinum, etc. retain their lustre because they do not react with air, water or acids. So they are called noble metals. Both metals and non-metals are used widely in our day to day life. 30  SECTION - A : SCIENTIFIC REASONING 1. The metal present in the hormone insulin is: 7. The property of the metal that is used to a. Fe b. Ag make musical instruments is: c. Zn d. Au a. Ductility b. Malleability c. Conductivity d. Sonority 2. X is a non-metal which is used in a purple colour solution considered as an antiseptic 8. Which of the following reactions is feasible? solution. Here X is: a. Zn + Cu2+ → Zn2+ + + Cu a. Iodine b. Bromine b. Fe + Zn2+ → Fe2+ + Zn c. Chlorine d. None of these c. Mg + Ca2+ → Mg2+ + Ca 3. Which of the following correctly d. None of these represents decreasing order of the 9. Which of the following metals will not reactivity of the metals? react completely with dilute sulphuric acid a. Potassium, calcium, zinc, lead to form a salt and hydrogen gas? b. Calcium, zinc, lead, potassium a. Calcium b. Lead c. Calcium, lead, zinc, potassium c. Magnesium d. Sodium d. Potassium, Calcium, lead, zinc 10. Which of the following statements is 4. The density of the metals is very high incorrect about aluminium? because they: a. Aluminium is a chemical element in the a. Are found in solid state. Boron group. b. Have closely packed atoms. b. It makes covalent compounds only. c. Are malleable. c. Aluminum is extracted from its ore bauxite. d. Are ductile. d. It is soft and brittle. 5. Which of the following pairs will give 11. Tooth cavities are filled with alloys of: displacement reactions? a. Silver b. Gold a. Magnesium chloride solution and c. Zinc d. Aluminium aluminium metal. b. Silver nitrate solution and copper metal. 12. The non-metal which is not affected by caustic soda is: c. Ferrous sulphate solution and silver metal. a. Phosphorus b. Silicon d. Sodium chloride solution and copper c. Sulphur d. Carbon metal 13. Which of the following is the electronic 6. Potassium carbonate is also known as configuration of metal with a high melting point? a. Pearlash b. Oil of vitrol a. 2, 1 b. 2, 8, 3 c. Glauber’s salt d. None of these c. 2, 8, 1 d. 2, 8, 8, 1 31 14. Why phosphorus is kept in water? a. I and III b. II and III I. It reacts very fast with atmospheric c. I, II and III d. None of these oxygen and catches fire. 15. Which of the following oxides cannot be II. It reacts fast with atmospheric reduced by both hydrogen gas and carbon nitrogen and catches fire. into its metals? III. Phosphorus being very reactive metal, a. CuO b. PbO will not be able to react with water molecules. c. ZnO d. CaO SECTION - B : EVERYDAY SCIENCE 16. Aluminium is used to make cooking 18. Which of the following statements utensils even though it is very high in the explains why 99.99% copper is used in reactivity series. Which of the following manufacturing high quality electrical wires statements justifies its use as a cooking for audio equipment? utensil? a. Copper is a good conductor of electricity. a. Aluminium has a much lower density b. Copper which is of a high purity can compared to iron. conduct electric current better. b. Aluminium loses three valence c. 99.99% copper is almost free of impurities. electrons readily during a chemical d. 99.99% copper is less ductile and cannot reaction. be stretched easily. c. Aluminium has a relatively high melting point compared to other metals. 19. Stainless steel is used to make utensils d. Aluminium can react readily with oxygen rather than iron metal. Which of the in the air to form aluminium oxide. following properties of stainless steel makes it better than iron? 17. Aman had three containers made of different materials to store pickles. a. Stainless steel is a good conductor and resistant to chemicals. b. Stainless steel is corrosion free and resistant to chemicals. c. Stainless steel is durable than iron metal. d. Both b. & c. Earthen jar Glass jar Aluminium jar 20. Aluminium and its alloys are used to build aircrafts, but not iron. Why? Which of these containers is a wrong choice for pickle storage and why? a. Aluminium alloys are lustrous. a. Container ‘P’ because it is made of soil. b. Iron is non-lustrous. b. Container ‘Q’ because glass is breakable. c. Aluminium alloys are used in aircrafts because they are light weight and c. Container ‘R’ because it is made of a corrosion free. metal which can react with pickles. d. Iron is lighter than aluminium metal. d. All are correct 32  SECTION - C : BRAINBOX 21. The given table shows the reactivity series of What will be the result of Zoei’s experiment metals. Identify correct option for X, Y and Z. if the metal is more reactive than carbon? X I. It will remain lit with a bright flame Most reactive Na Sodium producing black fragments (carbon). Ca Calcium II. It will remain lit with a bright flame Mg Magnesium producing white powder. Al Aluminium Zn Zinc III. No reaction will occur. Y Increasingly a. Only I Sn Tin reactive Pb Lead b. Only II Cu Copper c. Both I and II Mg Mercury d. None of these Z Au Gold Least reactive 23. Which of the following reactions will not take place easily? X Y Z a. K(s) + NaCl(aq) → KCl(aq) + Na(s) a. Potassium Iron Silver b. Mg(s) + Pb(NO3)2(aq) → Pb(s) + Mg(NO3)2(aq) b. Iron Sodium Diamond c. Zn(s) + Cu(NO3)2(aq) → Cu(s) + Zn(NO3)2(aq) d. 2AgNO3(aq) + Cu(s) → 2Ag(s) + Cu(NO3)2(aq) c. Silver Iron Sodium 24. Study the given figures. d. Iron Silver Sodium Blue solutions of XSO4 22. Zoei put a strip of burning metal in a jar filled Green solutions of XSO4 with carbon dioxide gas as shown in the diagram to check the reactivity of a metal. Brown layer Y filings of ‘X’ What are X and Y, respectively? a. Zn and Ag Gas jar b. Cu and Fe c. Fe and Cu Strip of burning metal d. Zn and Cu Carbon dioxide gas 33 25. Study the given table carefully and select the correct option. Sample Electrical Conductivity Malleability W   X   Y   Z   a. W – Cu, X – S b. X – S, Y – Coal c. Y – Fe, Z – Cu d. X – Coal, Z – Cu Darken your choice with HB pencil 1. a b c d 8. a b c d 15. a b c d 22. a b c d 2. a b c d 9. a b c d 16. a b c d 23. a b c d 3. a b c d 10. a b c d 17. a b c d 24. a b c d 4. a b c d 11. a b c d 18. a b c d 25. a b c d 5. a b c d 12. a b c d 19. a b c d 6. a b c d 13. a b c d 20. a b c d 7. a b c d 14. a b c d 21. a b c d 34 Chapter The Cell 7 ⇒ Robert Hooke observed the cork cells, which were dead cells. They appeared to him like small compartments so he called them ‘cells’. A cell is the smallest unit of life. All living things are made up of cells. Some organisms are made up of only one cell like - bacteria, paramecium and yeast. All species of animals, land plants, few species of fungi and algae contain more than one cell and are called multicellular organisms. Cells can be seen only under a microscope. It is an optical instrument used to see very tiny objects that we are unable to see with our naked eyes. ⇒ Plant cell – A plant cell has a nucleus, cytoplasm, a cell membrane and a cell wall. Some plant cells have chloroplast. Chloroplast contains chlorophyll which traps light energy needed for plants for the process of photosynthesis. Cell wall supports and gives the cell a regular shape. ⇒ Animal cell – An animal cell has a nucleus, cytoplasm, and a cell membrane. Nucleus controls all activities of the cell. It also stores genetic information. Cytoplasm is fluid that fills a cell. Cell membrane controls the movement of substances into and out of the cell 35  Which of the following is correct for the part labeled as P in the above diagram? a. It isSECTION - Ahouse called power : SCIENTIFIC of the cell REASONING b. It is called suicidal bag of the cell c. It is called control center of the cell 1. Jiya observed ad.cell under a microscope. a. Nucleus b. Antibody It is called kitchen of the cell She saw a transparent jelly- like substance c. Both a. and b. d. Chloroplast in the cell. What was that substance? Section-B: Thought Provoking7. X is the part of a cell that carries a. Cytoplasm b. Nucleus information that controls the characteristics c. Cell membrane d. Vacuole 16 What is the shape and size of cells that are to? related passed from one generation to the 2. The cell showna.in Size the diagram is ________. of the organism next generation. Identify X. b. Weight of the organism a. Chloroplast b. Cell membrane a. WBC c. Function of the cells b. RBC d. Number of cells c. Cytoplasm d. Nucleus 17. The given figure shows a unicellular c. Platelets 8. The given figure organism knownshows as amoeba Why there is no need for a anunicellular amoeba organism to have the d. None of these division of labour? known as amoeba. Why I It is inwhich 3. Identify the organelle contact with the surroundings directly is responsible there is no need for an II It obtain nutrients and removes waste products between the cell and for making proteins. amoeba to have division of labour? the surrounding a. Golgi complex a. Onlyb. I Ribosome I. It is in contact with the surroundings c. Chloroplastb. Onlyd. II Cell membrane directly. c. Both I and II II. It obtains nutrients and removes waste 4. Look at the diagram d. None shownof the above products between the cell and the here. Which of the following P 18. What is the benefit of having a divisionsurrounding. of labour in a multicellular living best describesorganism? the area marked as P? a. Only I b. Only II a. It contains8 genes. c. Both I and II d. None of these ISFO Practice Book b. Most of the cell processes take place here. 9. Identify the correct match. c. It controls the substances entering and I. Leucoplasts – The colourless plastids leaving the cell. II. Chloroplasts – The green coloured plastids d. It gives support to the cell. III. Chromoplasts – The coloured plastids 5. M  olly observed a cell under a microscope IV. Protoplasts – These are not plastids and concluded that it was a plant cell. Which of the following support her conclusion? a. I and II b. III and IV a. The cell had a almost rectangular shape. c. Both I and III d. All of these b. The cell membrane was present. 10. W  hich of the c. The cell had more cytoplasm. following is P d. None of these correct for the 6. The given figure shows the component of part labelled blood. Which of the following is present in as P in the above diagram? B but absent in A? a. It is the cytoplasm of the cell. b. It is called the suicidal bag of the cell. c. It is called the control centre of the cell. d. It is called the kitchen of the cell. 36 11. W  hat is true for the P 14. T he diagram shows four different cells as Q T animal cell shown in the seen through a microscope. diagram given here? Which of the following cell/cells has a S a. Oxidation of food R nucleus? takes place in Q. b. The central information of the cell is S. I. II. c. R is the jelly in which organelle floats. d. P controls entry into and out of the cell. III. IV. 12. Which of the following statements is /are correct? a. I only b. II and III only I. Cilia are present in Paramecium. c. II and IV only d. II, III and IV only II. Flagella are present in Euglena. 15. X  and Y are two cells. X is a dead cell while III. Cilia help in the growth of the cell. Y is a living cell. Which of the following IV. Both cilia and flagella help in movement. explains the correct difference between X and Y? a. Only IV b. Only III a. There is a change in the specific c. I, II and IV d. I and II organization of both X and Y. 13. Lysosomes are called suicide bag of the cell b. There is a change in the surrounding because atmosphere of both X and Y. I. These cause destruction of a cell c. The vital processes of X are destroyed through the action of its own enzymes. while the vital processes of Y are not II. Lysosomes engulf viruses and bacteria. destroyed. a. Only I b. Only II d. None of these c. Both I and II d. None of these SECTION - B : EVERYDAY SCIENCE 16. T he given diagram shows a small glass 17. What is the benefit of having division of object placed on the material which is to labour in a multicellular living organism? be mounted. This is called ______ and it is a. It reduces the energy requirement in a placed very cautiously to ______. multicellular living organism. b. It enables efficient functioning of the processes in a multicellular living organism. c. It reduces the waste products produced in a multicellular living a. Glass, avoid drying of the material organism. b. Cover slip, avoid air bubbles d. It enables the multicellular living c. Glass, increase visibility organism to defend the bacteria better. d. Glass slide, avoid folding of the material 37 18. J iya had a fall and had some bruises. Which the cell mounts, one should look for the of the following statements describes what presence or absence of: will happen to the cells in her body? a. Nucleus b. Plastid a. The cells which were knocked by the c. Peroxisomes d. Lysosomes fall will double themselves. b. The number of cells in the body will 20. Nerve cells help our body to connect and remain the same. communicate messages to our brain. Which of the following correctly explains c. New cells will be produced to replace the function of a nerve cell? the damaged cells. a. It brings about movement in the body d. The cells in the body will not be parts. affected by the fall. b. It carry message to and from the brain. 19. R  iya has prepared cheek cell mount and c. It gives protection to the underlying parts. Tina has