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22 Apr 2026

9th class Science Chapter Notes Key Questions (For 2026-27).

Preparing for the Maharashtra State Board (SSC) examinations involves more than just studying the textbooks. To excel, you must have organized notes and a thorough understanding of each 9th-class science chapter. As we commence the academic year 2026-27, it is essential to stay proactive with the syllabus. At EasyLearning, we offer your personal roadmap to success with our online tuition classes in Maharashtra, featuring streamlined notes and high-yield questions derived from previous exam papers. Reasons to Utilize Chapter-Wise Notes In each 9th class science chapter, specific topics are foundational for your 10th-grade Board exams. Whether it is the laws of physics in laws of motion or the in depth study of plant classification, having organized notes provides several benefits: Quick Revision: You won’t have to cram at the last moment before the exam.Concept Clarity: We explain in straightforward Hinglish and English.Enhanced Retention: Our notes include flowcharts and diagrams that aid understanding. Excel in your syllabus with 9th-class Online Classes Live. While reading notes is a great starting point, hearing an expert explain a challenging 9th class science chapter can significantly enhance your understanding. Our 9th class online classes live are designed to be highly engaging, which contributes to the success of all our students.Real-Time Doubts: Ask questions whenever you encounter difficulties.Numerical Mastery: In our live sessions, we tackle problems in physics and chemistry.Daily Updates: Don’t miss our free tips and concise chapter overviews on the EasyLearning YouTube channel. Key Topics for 2026-27: Based on the latest MH Board material, we present essential topics that every student should know.Laws of Motion: Can you demonstrate and validate Newton’s three laws through real-life examples?Work and Energy: Understanding the difference between potential energy and kinetic energy is crucial.Life Processes in Living Organisms: Be prepared to illustrate and label the human excretory and nervous systems. Upgrade to the Victory Batch, personalized 1-to-1 Guidance. If you’re struggling with any chapter of 9th class science on your own, it’s time to connect with our experts. At Victory Batch, we provide individualized online tuition classes in Maharashtra. Unlike free tutorials, our paid batch is designed specifically for the Maharashtra Board, which we describe as “aligned” (optimized). You will receive:Exclusive Test Series: Covering each topic in all chapters.Personal Mentorship: A dedicated space for addressing your academic concerns.Premium Notes: For the 2026-27 academic year, we offer downloadable PDFs that encompass all crucial topics.In conclusion, achieving success in Science requires regular effort. With these notes, our daily YouTube updates, and by enrolling, you can enhance your learning

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28 Mar 2026

Learn How To Achieve 95+ In Each 9th Class Science Chapter (Guide For 2026-2027).

Achieving a high score (95+) on your SSC exams is what everyone wants to do, and this can be accomplished through both hard work and a strategy to get you there. Preparing for large syllabi can be extremely overwhelming for students, but following a structured plan is the best way to approach and succeed in each of these 9th class science chapters, whether it’s physics laws (laws of motion, momentum, etc.) or complex biology topics. With the expansion of online learning to Maharashtra, there are many online resources available to learn complex topics in 9th class science. EasyLearning has helped thousands of students to better learn the MH Board Curriculum and be successful. Here is an easy step-by-step process for achieving a 95+ in 9th Class Science. Mastering The Foundation For Success In Each Individual 9th Class Science Chapter The most common mistake made by students is that they ‘memorize’ without understanding. To get above a 95+ in 9th Class Science chapter examinations you need to understand not just the concepts but also the relation between them. Conceptual Understanding – Take 2 chapters from 9th class Science, (Like, Laws of Motion and Work and Energy) – identify what ‘causes’ something (the ‘why’) to happen before you understand ‘how’ it will happen. Active Recall – Once you have completed a chapter study, close the book and write out 5 key points (from memory) that you can recall on that chapter. Practice Diagrams and Numericals In the Maharashtra Board (SSC), diagrams and numericals carry significant weightage. Practice labeling: Each weekend, choose one chapter and draw all the diagrams repeatedly until you can do them all perfectly. (For example, if you do Plant Classification this weekend, it will help you next weekend when you study plants again). Formula Sheets: Create a “formula bank” for every physics and chemistry chapter. Having all your formulas in one place makes last-minute revision a breeze. For daily updates and free classes, you can also check out the EasyLearning YT channel. Join the Victory 5.O Batch for 1-to-1 Guidance While self-study is important, scoring 95+ often requires a more personalized touch. For proper 1-to-1 guidance and a structured study environment, go for our paid Victory 5.O Batch. This is the gold standard for online education in Maharashtra, offering direct access to teachers, live doubt-clearing sessions, and a specialized test series designed to mirror the actual board exams. Practice Solving Previous Year Papers or PYQ’s In order to achieve a score of 95+, you need to understand the “language” of the examination by reviewing how each topic from every 9th class science chapter was assessed in prior years of the examination. This will allow you to perform a high-yield review of all sections of each chapter, as well as determine what information is generally considered supplementary. Your Path to Success Excellence is a habit. By pairing your commitment and drive to succeed with the guidance of experts in your field, you can develop the skills needed to convert even the most challenging topics from the class 9 Science curriculum into high-scoring assessments. Begin your path to a score of 95+ with the best online education in Maharashtra today!

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Maharashtra Board

26 Feb 2026

Observing Space : Telescopes Class 9 Science Chapter 18 Questions And Answers Maharashtra Board

1. Fill in the blanks with the proper words. a. The wavelength of visible light is between …….. and ………b. GMRT is used for ……. waves.c. A certain X-ray telescope is named after scientist ………..d. The first scientist to use a telescope for space observation was ………………. .e. The biggest optical telescope in India is situated at ………. Answer. (1) 400nm and 800nm (2) radio (3) Subramanian Chandrashekhar (4) Galileo (5) Nainital 2. Form pairs Column ‘A’ Column ‘B’ (1) X-rays (a) GMRT (2) Optical telescope (b) ISRO (3) Indian radio telescope (c) Hubble (4) Launching artificial-satellite (d) Chandra Answer. (1 – d),(2 – c),(3 – a),(4 – b), 3. What are the difficulties in using ground-based optical telescopes? How are they overcome? Answer. Difficulties: Solution: 4. Which type of telescopes can be made using a concave mirror, convex mirror, plane mirror, and a lens? Draw diagrams of these telescopes. Answer. 5. Study the figure and answer the following questions: a. What type of telescope is shown in the figure?b. Label the main parts of the telescope.c. Which type of mirror does the telescope use?d. What other type of telescope uses a curved mirror?e. Explain the working of the above telescope. Answer. (a) The Newtonian telescope (Reflecting telescope) (b) (c) Concave mirror (d) The Cassegrain telescope (e) Working. 6. Answer the following questions. a. Explain the construction of Galileo’s telescope. Answer. b. Explain the construction of a radio telescope. Answer. c. Why are optical telescopes located in uninhabited places on mountains? Answer. d. Why can an X-ray telescope not be based on the earth? Answer.

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Maharashtra Board

26 Feb 2026

Introduction to Biotechnology Class 9 Science Chapter 17 Questions And Answers Maharashtra Board

1. Each of the following statements is wrong. Rewrite them correctly by changing either one or two words. a. Simple squamous epithelium is present in respiratory tract.b. Glandular epithelium is present in kidneys.c. Chlorenchyma helps the plant to float in water.d. Striated muscles are also called involuntary muscles.e. Chloroplast is present in permanent tissue. Answer. a. False. Ciliated columnar epithelium is present in respiratory tract.b. False. Cuboidal epithelium is present in kidneys.c. False. Aerenchyma helps the plant to float in water.d. False. Striated muscles are also called voluntary muscles.e. False. Chlorenchyma is present in permanent tissue. 2.Identify the odd word and explain why it is odd. a. Xylem, phloem, permanent tissue, meristematic tissue. Answer. Meristematic tissue. It has the ability to divide whereas the others have lost the ability to divide. b. Epithelium, Muscle fibre, nerve fibre, the epidermis. Answer. Epidermis. It is a plant tissue whereas the others are animal tissues. c. Cartilage, bone, tendon, cardiac muscle. Answer. Cardiac muscle. It is a muscular tissue whereas the others are connective tissues. 3. Write the names of the following tissues. a. Tissue lining inner surface of mouth. Answer. Squamous epithelium. b. Tissue joining muscles and bones. Answer. Tendon c. Tissue responsible for increasing height of plants. Answer. Apical meristem. d. Tissue responsible for increasing girth of stem. Answer. Lateral meristem. 4. Write the differences.Simple tissue and complex tissues in plants. Answer. Simple Tissue in plants Complex Tissues in plants (i) They are made up of only one type of cells. (i) They are made up of more than one type of cells. (ii) They are found in all parts of the plant. (ii) They are found in the vascular regions of the plant. (iii) They perform different functions like storage (iii) They mainly perform the function of of food, support, giving strength etc. conduction of water and food. (iv) Examples – Parenchyma, Collenchyma, Sclerenchyma. (iv) Example – Xylem and phloem. 5. Write short notes. a. Meristematic tissue. Answer. b. Xylem Answer. c. Striated muscles. Answer. d. Agro-complementary business. Answer. (i) The business that are complementary to agriculture and generate supplementary income for the farmers are called agro complementary business. (ii) These include: e. Genetic engineering Answer. f. Sericulture Answer. 6. Explain the meaning of biotechnology and its impact on agricultural management with suitable examples. Answer. The techniques of bringing about improvements in living organisms by artificial genetic changes and by hybridization for the welfare of human beings, are together called biotechnology. Impact of biotechnology on agricultural management: 7.Which two main techniques are used in biotechnology? Why? Answer. 8. Discuss ‘Agritourism’ in the class and write a project on an agrotourism centre nearby. Present it in the class in groups. Answer. 9. Define the term tissue and explain the concept of tissue culture. Answer. A group of cells having the same origin, same structure and same function is called tissue. Concept of tissue culture: 10. ‘Rearing of sheep is a livestock’. Justify this statement. Answer.

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Maharashtra Board

26 Feb 2026

Heredity and Variation Class 9 Science Chapter 16 Questions And Answers Maharashtra Board

1. Complete the following sentences by choosing the appropriate words from the brackets.(Inheritance, sexual reproduction, asexual reproduction, chromosomes, DNA, RNA, gene) a. Hereditary characters are transferred from parents to off springs by …..………, hence they are said to be structural and functional units of heredity.b. Organisms produced by ……..……. show minor variations.c. The component which is in the nuclei of cells and carries the hereditary characteristics is called ……..……….d. Chromosomes are mainly made up of ………………e. Organisms produced through ……….…… show major variations. Answer. (1) gene (2) asexual reproduction (3) chromosome (4) DNA (5) sexual reproduction. 2. Explain following. a. Explain Mendel’s monohybrid progeny with the help of any one cross. Answer. b. Explain Mendel’s dihybrid ratio with the help of any one cross. Answer. c. Distinguish between monohybrid and dihybrid cross. Answer. Monohybrid cross Dihybrid cross (i) Cross involving a single pair of contrasting characters is called monohybrid cross. (i) Cross involving two pairs of contrasting characters is called a dihybrid cross. (ii) F1 plants of monohybrid cross produce two types of gametes. (ii) F1 plants of dihybrid cross produce four types of gametes. (iii) Monohybrid cross has a phenotypic ratio of 3 : 1 in F2 generation. (iii) Dihybrid cross has a phenotypic ratio of 9 : 3 : 3 : 1 in F2 generation. d. Is it right to avoid living with a person suffering from a genetic disorder ? Answer. 3. Answers the following questions in your own words. a. What is meant by ‘chromosome’. Explain its types. Answer. (a) Metacentric: The centromere is exactly at the mid-point in this chromosome, and therefore, it looks like the English letter ‘V’. The arms of this chromosome are equal in length. (b) Sub-metacentric: The centromere is somewhere near the mid-point in this chromosome which, therefore, looks like the English letter ‘U. One arm is slightly shorter than the other. (c) Acrocentric: The centromere is near one end of this chromosome which therefore looks like the English letter One arm is much smaller than the other. (d) Telocentric: The centromere is right at the end of this chromosome making the chromosome look like the English letter ‘i’. This chromosome consists of only one arm. b. Describe the structure of the DNA molecule. Answer. c. Express your opinion about the use of DNA fingerprinting. Answer. d. Explain the structure, function and types of RNA. Answer. e. Why is it necessary for people to have their blood examined before marriage? Answer. 4. Write a brief note on each. a. Down syndrome Answer. b. Monogenic disorders Answer. c. Sickle cell anaemia: symptoms and treatment. Answer. 5. How are the items in groups A, B and C inter-releated? Answer. 6. Filling the blanks based on the given relationship. a. 44+X:Turner syndrome: :44+XXY:- …………..b. 3:1 Monohybrid: : 9:3:3:1 : ………….c. Women : Turner syndrome : : Men : ……. Answer. a. Klinefelter syndromeb. Dihybridc. Klinefelter syndrome 7. Complete the tree diagram below based on types of hereditary disorders. Answer.

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Maharashtra Board

25 Feb 2026

Life Processes in Living Organisms Class 9 Science Chapter 15 Questions And Answers Maharashtra Board

1. Match the pairs and explain. Answer. (1 – b),(2 – c),(3 – a),(4 – e) 2. Complete the paragraph. The milk was on the stove. Rasika was engrossed watching television. She smelled something burning. She ran towards the kitchen. The milk was boiling over. She held the vessel with her bare hands but, screaming, she let it go at once. This activity was controlled by ……………….. cells. Special ends of ……………….. in these cells collected the information, from where it was transferred to the ……………….. and then towards the terminal end of the ……………….. The chemicals produced at the terminal end passed through the minute space i.e. ………………. . In this way, ……………….. were conducted in the body and the process of ……………….. was completed by conducting the impulses from ……………….. to ……………… (Nerve, muscle cell, impulse, dendrite, synapse, axon, reflex action, cell body) Answer. Nerve, dendrite, cell body, axon, synapse, impulses, reflex action, nerve, muscle cell. 3. Write notes on Root pressure, Transpiration, Nerve cell, Human brain, Reflex action Answer. 1. Root pressure (1) The pressure created in the root cells is called a root pressure. Root cells are in contact with water and minerals in the soil. But the concentration inside the cells and the concentration in the surrounding soil is different from each other and thus there is concentration gradient created. (2) Due to concentration gradient, the water and minerals from the surrounding areas enter in the root cells. (3) Due to this, the root cells become turgid and exert pressure on the adjacent cells. (4) Due to root pressure, the water and minerals enter the xylem present in the roots. To reduce this difference in concentration they are continuously pushed forward. This continuous movement creates a water column that is continuously pushed ahead. (5) The pressure exerted by the root cells thus is sufficient to lift the water up in small shrubs and small trees. 2. Transpiration (1) There are stomata on the leaves of the plants. Through these opening the excess of water is thrown out in the form of water vapours. This process is called transpiration. (2) There are two guard cells around the opening of stomata. They have an external membrane. They control the opening and closing of the stomata. (3) Also some amount of water is lost due to evaporation from the leaves. (4) As a result, water level in the epidermal layer of the leaf decreases. (5) To compensate this loss, more water is brought to the leaves through the xylem. (6) Transpiration thus helps in absorption of water and minerals and their distribution to all parts of the plant. (7) Root pressure pushes the water up during the night time. 3. Nerve cell (1) Neurons or nerve cells are structural and functional units of the nervous system that carry impulses from one place to other. (2) Neuron has the ability to generate and conduct electrochemical impulses. (3) Every neuron has three main parts, viz. cyton or cell body, axon and dendrites. Dendrites pick up the electrochemical signals produced. (4) These signals are transferred to cyton and from cyton they are sent to axons. From axon of one neuron, the impulse is then given to dendrites of next neuron. 4. Human brain (1) Human brain is highly evolved organ. It is the main controlling centre of nervous system. It is the part of the central nervous system. It is very well protected inside the cranium or cranial cavity. (2) The brain is enclosed by meninges which are protective coverings. There are hollow ventricles inside the brain which are filled up with cerebrospinal fluid. This fluid is protective and nourishing in function. The average weight of adult human brain is about 1300 – 1400 grams and there are approximately 100 billion neurons in the brain. (3) There are three main parts of the brain, viz. Cerebrum, cerebellum and medulla oblongata. 5. Reflex action (1) Reflex action is an immediate and involuntary response given to a stimulus from the environment. (2) The reflex action is so spontaneous that it does not require thinking or control by our brain. (3) Reflex actions are not controlled by brain. But the control and coordination is maintained by the reflex actions by which the load on the brain isreduced. They are of survival value as a person is saved from a dangerous situations due to reflex actions. (4) The path of reflex action is as follows : This is also known as reflex arc. Sense organs Sensory neurons -> Towards the spinal cord -> Coordination neuron -> Motor neuron-> Muscle or gland. 4. Name the hormones of the following endocrine glands and the function of each. Pituitary, Thyroid, Adrenal, Thymus, Testis, Ovary. Answer. Hormone Function (i) Growth hormone Stimulates growth of bones. (ii) Adrenocorticotropic hormone Stimulates adrenal gland. (iii) Thyroid-stimulating hormone Stimulates thyroid gland. (iv) Prolactin Stimulates milk production. (v) Follicle-stimulating hormone Controls growth of gonads. (vi) Luteinizing hormone Controls menstrual cycle and ovulation. (vii) Oxytocin Contracts uterus during parturition. (viii) Antidiuretic hormone Regulates water-level in the body. 2. Thyroid Hormone Function (i) Thyroxine Controls growth of body and metabolic activities. (ii) Calcitonin Controls calcium metabolism and calcium level in blood. 3. Adrenal Hormone Function (i) Adrenalin and nor-adrenalin Controls behaviour during crisis and emotional situation. (ii) Corticosteroid Maintains balance of Na+ and K+ and stimulates metabolism. 4. Thymus Hormone Function Thymosin Control the cells which give rise to immunity. 5. Testis Hormone Function Testosterone Stimulates growth of secondary sexual characteristics like beard, mustache, hoarse voice etc. in men. 6. Ovary Hormone Function (i) Oestrogen Stimulates growth of the endometrium. Stimulates growth of secondary sexual characteristics in women. (ii) Progesterone Prepares the endometrium for conception and maintains pregnancy. 5. Draw and label the diagrams. Human endocrine glands, Human brain, Nephron, Nerve cell, Human excretory system. Answer. 1. Human endocrine glands 2. Human brain 3. Nephron 4. Nerve cell 5. Human excretory system 6. Answer the following. a. Explain chemical co-ordination in humans and give the names and

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Maharashtra Board

25 Feb 2026

Substances in Common Use Class 9 Science Chapter 14 Questions And Answers Maharashtra Board

1. Fill in the blanks. a. The number of molecules of water of crystallization in washing soda is ………….b. The chemical name of baking soda is ………….c. …………. is used in treatment of hyperthyroidism.d. The chemical name of Teflon is …………. Answer. a. 10b. Sodium bicarbonatec. Iodine -123d. Polytetra fluoroethylene (C2F4)n 2. Match the pairs Group A Group B 1. Saturated brine a. sodium metal freed 2. Fused salt b. basic salt 3. CaOCl2 c. crystallization of salt 4. NaHCO3 d. oxidation of colour Answer. (1 – c)(2 – a)(3 – d)(4 – b) 3. Write answers to the following a. What is meant by radioactivity ? Answer. b. When is the nucleus said to be unstable ? Answer. c. Which diseases are caused by artificial food colours ? Answer. Diseases like ADHD (Attention Deficit Hyperactivity Disorder) can affect children due to excessive consumption of foods with added food colours. d. Where in the industrial field is radioactivity used ? Answer. Industrial field Radiography Measurement of thickness, density and level Luminescent paint and radio luminescence: Use in Ceramic articles: e. Write down properties of teflon. Answer. Properties of teflon : f. What type of colours will you use to celebrate ecofriendly Rang Panchami? Why? Answer. g. Why has the use of methods like Teflon coating become more common? Answer. The use of methods like Teflon coating became more common because of following properties of teflon: 4. Give a scientific explanation a. Bleaching powder has the odour of chlorine. Answer. b. The hard water of a well becomes soft on adding washing soda to it. Answer. c. Soap forms a precipitate in hard water. Answer. d. The particles of powder are given an electric charge while spraying them to form the powder coating. Answer. e. The aluminium article is used as an anode in the anodising process. Answer. f. When the radiation coming out from certain radioactive substance is passed through an electric field, marks are found at three places on the photographic plate placed in its path. Answer. (i) When the radiation coming out from certain radioactive substance is passed through an electric field, marks are found at three places on the photographic plate placed in its path. This is because the radiation coming out from radioactive substance are of three types Alpha rays, Beta rays and Gamma rays. (ii) The rays which get deviated slightly towards negatively charged plate are called alpha rays. They get deviated towards negatively charged plate because they are made of positively charged particles, called as alpha particles (He++). (iii) The rays which get deviated substantially towards the positively charged plate are called beta rays. They get deviated towards a positively charged plate because they are made of negatively charged particles called as beta particles (e-). (iv) The rays which do not deviate at all are called gamma rays. They are uncharged electromagnetic radiation. Hence, marks are found at three places on the photographic plate. g. A certain type of ceramic tiles are fixed on the outer layer of a space shuttle. Answer. (i) Each shuttle is covered by more than 24,000 of the six- by six-inch advance ceramic tiles. This tiles withstand high temperatures without decomposing. They are brittle, water-resistant and electrical insulator. Most of the tiles are made of silica fibres, which are produced from high-grade sand (SiO2). (ii) Silica is an excellent insulator because it transports heat slowly. When the outer portion of a tile gets hot, the heat takes a long time to work its way down through the rest of the tile to the shuttle’s skin. The tiles keep the orbiter’s aluminium skin at 350 degrees or less. (iii) The silica fibers are mixed with water and chemicals, and the mixture is poured into molds, which are zapped in microwave ovens at 2,350°C to fuse the silica fibres. Tiles are too brittle to attach to the orbiter directly. (iv) The shuttle’s skin contracts slightly while in orbit, then expands during re-entry. (v) In addition, the stresses of launch and re-entry cause the skin to flex and bend. Such motions could easily crack the tiles or shake them off. To keep them in place, workers glue the tiles to flexible felt-like pads, then glue the pads to the orbiter. 5. Write answers to the following a. Write about artificial food colours, the substances used in them and their harmful effects. Answer. (a) Artificial food colour and substances in them. (b) Harmful effects of artificial food colours b. What is meant by water of crystallization? Give examples of salts with water of crystallization, and their uses. Answer. The exact number of water molecules which are chemically bonded to a molecule of a salt within a hydrated crystalline compound is called as water of crystallization are: Some substances in our daily use which contain water of crystallization are: Uses of these salts are as given below:(i) Alum (Potash alum – K2SO4.Al2(SO4)3.24H2O) (ii) Borax (Na2B4O7.10H2O) (iii) Epsom salt (Magnesium sulphate MgSO4.7H2O) (iv) Barium chloride (BaCl2.2H2O) (v) Sodium sulphate (Glauber’s salt Na2SO4.10H2O) (vi) Blue vitriol (Copper sulphate CuSO4.5H2O) c. Write briefly about the three methods of electrolysis of sodium chloride. Answer. 6. Write the uses.a. Anodizing b. Powder coating c. Radioactive substances d. Ceramic Answer. (a) Anodizing : Anodizing is done on aluminum cooking utensils like griddles and cookers. (b) Powder coating : Powder coating is done on iron objects to prevent rusting. Also, on Plastic and Medium density fibre (MDF) board, to make them highly durable, hard and attractive. (c) Radioactive substances:(I) Industrial field:(i) Industrial Radiography : Internal cracks and voids in cast iron articles and iron solder can be. detected with the help of gamma rays. For this purpose, isotopes like cobalt-60, iridium-192 are used in the radiography camera. This technique is used for detecting flaws in metal work. (ii) Measurement of thickness, density and level: It is necessary to maintain the required thickness in the manufacture of aluminium, plastic, iron sheets of differing thickness. In the manufacturing process, a radioactive substance

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Maharashtra Board

25 Feb 2026

Carbon : An important element Class 9 Science Chapter 13 Questions And Answers Maharashtra Board

1. Select the proper option and complete the statements(single, all, double, ionic, carbon, give and take, hydrogen, multiple, share, most, covalent) a. A carbon atom forms a …….… bond with other atoms. In this bond the two atoms ……..electrons.b. All the carbon bonds in a saturated hydrocarbon …….…. electrons.c. At least one carbon bond in an unsaturated hydrocarbon is ……….d. ………. is the essential element in all the organic compounds.e. The element hydrogen is present in ………. organic compound. Answer. (a) covalent, share (b) share (c) multiple (d) Carbon (e) all 2. Answer the following questions a. Why are carbon and its compounds used as fuels ? Answer. (i) The name ‘carbon’ is derived from Latin word ‘carbo’meaning coal. In the earth’s crust, carbon is present to an extent of approximately 0.27% in the form of carbonate, coal and petroleum. One of the non-crystalline and amorphous form of carbon is coal. Coal is a fossil fuel. (ii) Peat, lignite, bituminous and anthracite are the four types of coal in the increasing order of their carbon content and heat produced respectively. Charcoal and coke are the other amorphous forms of carbon used as fuel. (iii) Compounds of carbon such as hydrocarbons consist of carbon and hydrogen and they are easily combustible. For example, methane (CH4) which occurs in natural gas is highly inflammable. It bums by reacting with oxygen to give a bluish flame. In this reaction, 213 Kcal/mol of heat is given out. Methane bums completely. Chemical reaction:CH4 + 2O2 → CO2 + 2H2O + Heat (iv) Thus when hydrocarbons are burnt in air, large amount of heat is evolved with formation of carbon dioxide (CO2) and water (H2O). Due to evolution of heat on combustion, carbon and its compounds are used as fuels. b. In which compound forms does carbon occur ? Answer. Carbon in its combined state exists as various compounds such as: c. Write the uses of diamond. Answer. Uses of diamonds are: 3. Explain the difference: a. Diamond and graphite. Answer. Diamond Graphite (i) Diamond is a brilliant, hard and crystalline allotrope of carbon. (i) Graphite is a black, soft, brittle and slippery crystalline allotrope of carbon. (ii) In diamonds, every carbon atom is bonded to four neighbouring atoms by covalent bonds forming tetragonal three dimensional structure which makes it very hard. (ii) In graphite, every carbon atom is bonded to three other carbon atoms by covalent bonds in such a way that a hexagonal layered structure is formed. A graphite crystal is made of many such layers of carbon atoms. These layers slip over each other on applying pressure. (iii) Density of diamond is 3.5 g/cm3. (iii) Density of graphite is 1.9 to 2.3 g/cm3. (iv) Diamond is a bad conductor of electricity as it does not have free electrons. (iv) Inside each layer of graphite, free electrons move continuously within the entire layer. Hence, graphite is a good conductor of electricity. b. Crystalline and non-crystalline forms of carbon. Answer. Crystalline forms of carbon Non-crystalline forms of carbon (i) A crystalline form has a regular and definite arrangement of atoms.(ii) They have high melting points and boiling points.(iii) A crystalline form has a definite geometrical shape, sharp edges and plane surfaces.(iv) Diamond, graphite and fullerene are different crystalline forms of carbon. (i) A non-crystalline form does not have a regular and definite arrangement of atoms.(ii) They have low melting points and boiling points.(iii) They are amorphous, hence, they do not have definite geometrical shape.(iv) Coal, charcoal and coke are different noncrystalline/amorphous forms of carbon. 4. Write scientific reasons a. Graphite is a conductor of electricity. Answer. b. Graphite is not used in ornaments. Answer. c. Limewater turns milky when CO2 is passed through it. Answer. d. Biogas is an eco-friendly fuel. Answer. 5. Explain the following. a. Diamond, graphite and fullerenes are crystalline forms of carbon. Answer. b. Methane is called marsh gas. Answer. c. Petrol, diesel, coal are fossil fuels. Answer. (i) A fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms. Fossil fuels contain high percentage of carbon. The word carbon is derived from the Latin word ‘Carbo’ meaning coal. (ii) Coal is formed from the remains of trees and other vegetation. Approximately 350 million years ago, these remains were trapped on the bottom of swamps, accumulating layer after layer and creating a dense material called peat. As this peat was buried under more and more ground, the high temperature and pressure transformed it into coal. (iii) Petrol and diesel are obtained from mineral oil. Mineral oil also called as crude oil or petroleum oil is formed from the remains of plants and animals that lived in the seas millions of years ago. This plant and animal matter has been drawn down and subjected to extremes of temperature and pressure over millions of years ago. (iv) Mineral oil is commonly formed in rocks under the sea bed. The word petroleum is derived from Latin word ‘Rock oil’. Petrol and Diesel are obtained from mineral oil by the process called as fractional distillation.Thus petrol, diesel and coal are fossil fuels. d. Uses of various allotropes of carbon. Answer. e. Use of CO2 in fire extinguisher. Answer. f. Practical uses of CO2. Answer. Practical uses of CO2 are: 6. Write two physical properties each. a. Diamond Answer. Properties of diamond are: b. Charcoal Answer. c. Fullerene Answer. 7. Complete the following Chemical reactions. 1. ………………..+………………..→ CO2 + 2H2O + Heat2. ………………..+………………..→ CH3Cl + HCl3. 2 NaOH + CO2 →………………..+……………….. Answer. 8. Write answers to the following in detail. a. What are the different types of coal? What are their uses? Answer. Coal is a fossil fuel. It contains carbon, hydrogen and oxygen. It also contains nitrogen, phosphorus and sulphur. It occurs in the solid state. It is of four types. Uses of coal: b. How will you prove experimentally that graphite is good conductor of electricity? Answer. Apparatus required: Lead pendi, electrical wires, battery/cell, small bulb, etc. Step-I: Remove the lead from

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Maharashtra Board

24 Feb 2026

Study of Sound Class 9 Science Chapter 12 Questions And Answers Maharashtra Board

1. Fill in the blanks and explain. a. Sound does not travel through………… Answer. Vacuum b. The velocity of sound in steel is …………… than the velocity of sound in water. Answer. Greater c. The incidence of ……… in daily life shows that the velocity of sound is less than the velocity of light. Answer. (i) An Airplane is seen first and its sound is heard later. (ii) lightning is seen first and thunder is heard later. d. To discover a sunken ship or objects deep inside the sea, ………………….. technology is used. Answer. Sonar 2. Explain giving scientific reasons. a. The roof of a movie theatre and a conference hall is curved. Answer. b. The intensity of reverberation is higher in a closed and empty house. Answer. c. We cannot hear the echo produced in a classroom. Answer. 3. Answer the following questions in your own words. a. What is an echo? What factors are important to get a distinct echo? Answer. b. Study the construction of the Golghumat at Vijapur and discuss the reasons for the multiple echoes produced there. Answer. c. What should be the dimensions and the shape of classrooms so that no echo can be produced there? Answer. 4. Where and why are sound absorbing materials used? Answer. The sound absorbing materials are used in : 5. Solve the following examples. a. The speed of sound in air at O °C is 332 m/s. If it increases at the rate of 0.6 m/s per degree, what will be the temperature when the velocity has increased to 344 m/s? Answer. Given:Initial speed of sound at 0°C 332 m/s.Final speed of sound -344 m/s.Rate of increase per degree rise in temp. = 0.6m/sTo find:Temperature when speed is 344m/sFormulae: Temperature when the speed of sound is 344 m/sis 20°C b. Nita heard the sound of lightning after 4 seconds of seeing it. What was the distance of the lightning from her? (The velocity of sound in air is 340 m/s?) (Ans: 1360 m) Answer. Given : Speed of sound (v) = 340 m/sTime taken (f) = 4 secTo find : Distance (s) = ? The lightning has struck at a distance of 1360 m from the observer. c. Sunil is standing between two parallel walls. The wall closest to him is at a distance of 660 m. If he shouts, he hears the first echo after 4 s and another after another 2 seconds. 1.What is the velocity of sound in air? 2.What is the distance between the two walls? (Ans: 330 m/s; 1650 m) Answer. Given:Distance of the closer wall (S1) = 660 mTime of echo from closer wall = 4 sec∴ Time taken (t1) = 4/2 sec = 2 secTime of echo from distant wall = 6 sec∴ Time taken (t2) = 6/2 sec = 3 secTo find :Velocity of sound in air (y) =?Distance between two walls (S1 + S2) = ? The velocity of sound in air is 330 mIs and the distance between two walls is 1650 m. d. Hydrogen gas is filled in two identical bottles, A and B, at the same temperature. The mass of hydrogen in the two bottles is 12 gm and 48 gm respectively. In which bottle will sound travel faster? How may times as fast as the other? (Ans: In A; Twice) Answer. Hence, sound will travel faster in bottle A and its speed will be twice as that of bottle B. e. Helium gas is filled in two identical bottles A and B. The mass of the gas in the two bottles is 10 gm and 40 gm respectively. If the speed of sound is the same in both bottles, what conclusions will you draw? (Ans: Temperature of B is 4 times the temperature of A.) Answer. Given:Mass of Helium in bottle A = (mA) = 10gmMass of Helium in bottle B = (mB) = 40gm The temperature of B is 4 times the temperature of A

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