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            <h1>Class X Science</h1>
            <p>Generate Customized Assignments</p>
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                            <label for="chapter1">1. Chemical Reactions and Equations</label>
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                            <label for="chapter2">2. Acids, Bases and Salts</label>
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        const questions = {
            "Chapter 1": {
                mcq: [
                    { question: "Which of the following is a characteristic of a chemical reaction?", options: ["Change in state", "Change in color", "Evolution of gas", "All of the above"], answer: "All of the above" },
                    { question: "The reaction between magnesium and oxygen is an example of:", options: ["Combination reaction", "Decomposition reaction", "Displacement reaction", "Double displacement reaction"], answer: "Combination reaction" },
                    { question: "Which of the following is an example of an endothermic reaction?", options: ["Respiration", "Photosynthesis", "Burning of fuel", "Rusting of iron"], answer: "Photosynthesis" }
                ],
                assertionReason: [
                    { 
                        assertion: "In a chemical reaction, the total mass of the reactants is equal to the total mass of the products.", 
                        reason: "Law of conservation of mass states that mass can neither be created nor destroyed in a chemical reaction.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "Rusting of iron is a physical change.", 
                        reason: "In rusting, a new substance (iron oxide) is formed.",
                        answer: "A is false but R is true."
                    }
                ],
                veryShort: [
                    "What is a balanced chemical equation? Why should chemical equations be balanced?",
                    "Why is respiration considered an exothermic reaction?"
                ],
                short: [
                    "Write the balanced chemical equation for the reaction between sodium hydroxide and hydrochloric acid.",
                    "Explain the difference between combination and decomposition reactions with examples."
                ],
                long: [
                    "What is corrosion? Explain the conditions necessary for rusting of iron. How can rusting be prevented?",
                    "Explain the various types of chemical reactions with suitable examples for each type."
                ],
                caseStudy: [
                    {
                        context: "A student performed an experiment where he took about 2g of ferrous sulphate crystals in a dry boiling tube and heated it.",
                        questions: [
                            "What changes would you observe during the heating process?",
                            "Write the chemical equation for the reaction taking place."
                        ]
                    }
                ]
            },
            "Chapter 2": {  
                mcq: [
                    { question: "Which of the following is not a property of acids?", options: ["Sour taste", "Turn blue litmus red", "Release H+ ions in water", "Soapy feel"], answer: "Soapy feel" },
                    { question: "The pH of a neutral solution is:", options: ["0", "7", "10", "14"], answer: "7" },
                    { question: "Which of the following is a weak acid?", options: ["Hydrochloric acid", "Sulphuric acid", "Nitric acid", "Acetic acid"], answer: "Acetic acid" }
                ],
                assertionReason: [
                    { 
                        assertion: "Sodium hydroxide is used in the manufacture of soap.", 
                        reason: "Sodium hydroxide reacts with oils/fats to form soap.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "All bases are alkalis.", 
                        reason: "Bases that are soluble in water are called alkalis.",
                        answer: "A is false but R is true."
                    }
                ],
                veryShort: [
                    "What is the chemical name of baking soda? Write its chemical formula.",
                    "Why does distilled water not conduct electricity whereas rainwater does?"
                ],
                short: [
                    "How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?",
                    "What happens when chlorine is passed through slaked lime? Write the chemical equation."
                ],
                long: [
                    "Explain the process of neutralization with the help of an example. How is this process useful in everyday life?",
                    "What is pH? How is it important in everyday life? Give examples."
                ],
                caseStudy: [
                    {
                        context: "A farmer found that the soil in his field was too acidic. He was advised to add quick lime to the soil.",
                        questions: [
                            "Why was the farmer advised to add quick lime to the soil?",
                            "What is the chemical name of quick lime? Write its chemical formula."
                        ]
                    }
                ]
            },
            "Chapter 3": {  
                mcq: [
                    { question: "Which of the following metals is stored in kerosene?", options: ["Iron", "Copper", "Sodium", "Gold"], answer: "Sodium" },
                    { question: "The most abundant metal in the earth's crust is:", options: ["Iron", "Aluminum", "Copper", "Calcium"], answer: "Aluminum" },
                    { question: "Which of the following metals reacts vigorously with oxygen and water?", options: ["Copper", "Silver", "Potassium", "Mercury"], answer: "Potassium" }
                ],
                assertionReason: [
                    { 
                        assertion: "Aluminum is used for making cooking utensils.", 
                        reason: "Aluminum is a good conductor of heat and forms a protective oxide layer.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "Gold and platinum are used to make jewelry.", 
                        reason: "Gold and platinum are highly reactive metals.",
                        answer: "A is true but R is false."
                    }
                ],
                veryShort: [
                    "Why are metals good conductors of electricity?",
                    "Name two metals that are found in nature in the free state."
                ],
                short: [
                    "Explain why the surface of some metals acquires a dull appearance when exposed to air for a long time.",
                    "What happens when iron nails are placed in copper sulphate solution? Write the chemical equation."
                ],
                long: [
                    "Explain the process of extraction of metals in the middle of the activity series with suitable examples.",
                    "What is corrosion? Explain the conditions necessary for rusting of iron. How can rusting be prevented?"
                ],
                caseStudy: [
                    {
                        context: "A student took four test tubes marked I, II, III and IV. He put iron nails in each of them and poured different solutions in each test tube.",
                        questions: [
                            "In which test tube would the iron nail rust the most? Why?",
                            "What method can be used to prevent rusting in this case?"
                        ]
                    }
                ]
            },
            "Chapter 4": {  
                mcq: [
                    { question: "Which of the following is the molecular formula of butane?", options: ["C4H10", "C3H8", "C2H6", "CH4"], answer: "C4H10" },
                    { question: "The functional group present in alcohols is:", options: ["-CHO", "-COOH", "-OH", "-CO-"], answer: "-OH" },
                    { question: "Which of the following is used as an antiseptic?", options: ["Ethanol", "Methanol", "Acetic acid", "Formic acid"], answer: "Ethanol" }
                ],
                assertionReason: [
                    { 
                        assertion: "Carbon forms a large number of compounds.", 
                        reason: "Carbon has the unique ability to form bonds with other carbon atoms (catenation).",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "Ethanoic acid is commonly called glacial acetic acid.", 
                        reason: "Ethanoic acid freezes in cold weather forming ice-like crystals.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    }
                ],
                veryShort: [
                    "What is the difference between saturated and unsaturated hydrocarbons?",
                    "Name the functional group present in (i) ethanol (ii) ethanoic acid"
                ],
                short: [
                    "What is a homologous series? Explain with an example.",
                    "Why does micelle formation take place when soap is added to water?"
                ],
                long: [
                    "Explain the formation of scum when hard water is treated with soap. How is this problem overcome by using detergents?",
                    "What are esters? How are they prepared? List two uses of esters."
                ],
                caseStudy: [
                    {
                        context: "A student was given four samples labeled A, B, C and D. The samples were ethanol, ethanoic acid, soap solution and distilled water.",
                        questions: [
                            "How can the student identify each sample using chemical tests?",
                            "Write the chemical equation for the reaction between sample A and sample B in the presence of concentrated sulphuric acid."
                        ]
                    }
                ]
            },
            "Chapter 5": {  
                mcq: [
                    { question: "The modern periodic table is based on:", options: ["Atomic mass", "Atomic number", "Number of neutrons", "Number of isotopes"], answer: "Atomic number" },
                    { question: "Which of the following elements has the smallest atomic radius?", options: ["Sodium", "Magnesium", "Aluminum", "Silicon"], answer: "Sodium" },
                    { question: "The element with electronic configuration 2,8,7 is:", options: ["Fluorine", "Chlorine", "Bromine", "Iodine"], answer: "Chlorine" }
                ],
                assertionReason: [
                    { 
                        assertion: "Elements in the same group have similar chemical properties.", 
                        reason: "Elements in the same group have the same number of valence electrons.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "Atomic size decreases from left to right across a period.", 
                        reason: "Nuclear charge increases across the period while the number of shells remains the same.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    }
                ],
                veryShort: [
                    "State Mendeleev's periodic law.",
                    "Why do all the elements of the same group have similar properties?"
                ],
                short: [
                    "How does the metallic character of elements change as we move (i) from left to right in a period (ii) down a group?",
                    "How does the atomic size vary in a period and in a group? Give reasons."
                ],
                long: [
                    "Compare and contrast the arrangement of elements in Mendeleev's periodic table and the modern periodic table.",
                    "Explain the trends in the following properties of elements in the periodic table: (i) Valency (ii) Metallic character"
                ],
                caseStudy: [
                    {
                        context: "Three elements A, B and C have atomic numbers 11, 17 and 18 respectively.",
                        questions: [
                            "Identify the group and period of each element in the modern periodic table.",
                            "Which of these elements would have similar chemical properties and why?"
                        ]
                    }
                ]
            },
            "Chapter 6": {  
                mcq: [
                    { question: "Which of the following is not a life process?", options: ["Respiration", "Reproduction", "Excretion", "Combustion"], answer: "Combustion" },
                    { question: "The site of photosynthesis in plants is:", options: ["Mitochondria", "Chloroplast", "Nucleus", "Ribosome"], answer: "Chloroplast" },
                    { question: "The process of breakdown of glucose in the absence of oxygen is called:", options: ["Glycolysis", "Fermentation", "Krebs cycle", "Electron transport chain"], answer: "Fermentation" }
                ],
                assertionReason: [
                    { 
                        assertion: "Plants have low energy needs as compared to animals.", 
                        reason: "Plants do not move from one place to another.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "The human heart has four chambers.", 
                        reason: "This prevents the mixing of oxygenated and deoxygenated blood.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    }
                ],
                veryShort: [
                    "Name the pigment present in plants which is responsible for absorption of sunlight.",
                    "What is the role of acid in our stomach?"
                ],
                short: [
                    "How is the small intestine designed to absorb digested food?",
                    "What are the differences between aerobic and anaerobic respiration?"
                ],
                long: [
                    "Describe the process of nutrition in amoeba with the help of a diagram.",
                    "Explain the process of double circulation in human beings. Why is it necessary?"
                ],
                caseStudy: [
                    {
                        context: "A student set up an experiment to show that carbon dioxide is given out during respiration. He took two thermos flasks A and B. Flask A had germinating seeds while flask B had dry seeds.",
                        questions: [
                            "Which flask would show the presence of carbon dioxide and why?",
                            "What would be the observation if lime water is kept in both flasks?"
                        ]
                    }
                ]
            },
            "Chapter 7": {  
                mcq: [
                    { question: "The gap between two neurons is called a:", options: ["Dendrite", "Synapse", "Axon", "Impulse"], answer: "Synapse" },
                    { question: "Which plant hormone promotes cell division?", options: ["Auxin", "Gibberellin", "Cytokinin", "Abscisic acid"], answer: "Cytokinin" },
                    { question: "The movement of shoot towards light is:", options: ["Geotropism", "Hydrotropism", "Chemotropism", "Phototropism"], answer: "Phototropism" }
                ],
                assertionReason: [
                    { 
                        assertion: "Electrical impulses are an efficient means of communication in animals.", 
                        reason: "Electrical impulses travel quickly and reach all parts of the body.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "Abscisic acid is called the stress hormone in plants.", 
                        reason: "Abscisic acid inhibits growth during stressful conditions.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    }
                ],
                veryShort: [
                    "What is the function of receptors in our body?",
                    "Name the part of the brain that controls posture and balance of the body."
                ],
                short: [
                    "How does chemical coordination take place in animals?",
                    "What are reflex actions? Give two examples."
                ],
                long: [
                    "Draw the structure of a neuron and explain its function.",
                    "Compare and contrast the nervous and hormonal mechanisms for control and coordination in animals."
                ],
                caseStudy: [
                    {
                        context: "A doctor advised a patient to reduce sugar intake as his blood sugar level was high. The patient was also advised to take insulin injections.",
                        questions: [
                            "Name the disease the patient is suffering from and the hormone whose deficiency causes it.",
                            "Why was the patient advised to take insulin injections?"
                        ]
                    }
                ]
            },
            "Chapter 8": {  
                mcq: [
                    { question: "Which of the following is not a part of the female reproductive system in human beings?", options: ["Ovary", "Uterus", "Vas deferens", "Fallopian tube"], answer: "Vas deferens" },
                    { question: "The anther contains:", options: ["Sepals", "Ovules", "Pollen grains", "Carpel"], answer: "Pollen grains" },
                    { question: "Asexual reproduction in Spirogyra involves:", options: ["Binary fission", "Budding", "Fragmentation", "Spore formation"], answer: "Fragmentation" }
                ],
                assertionReason: [
                    { 
                        assertion: "Variation is beneficial to the species.", 
                        reason: "It enables the species to adapt to changing environmental conditions.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "Zygote is formed inside the ovary.", 
                        reason: "Fertilization occurs in the ovary.",
                        answer: "A is true but R is false."
                    }
                ],
                veryShort: [
                    "What is the importance of DNA copying in reproduction?",
                    "Name the reproductive and non-reproductive parts of a flower."
                ],
                short: [
                    "How does the embryo get nourishment inside the mother's body?",
                    "What are the advantages of vegetative propagation?"
                ],
                long: [
                    "Explain the various methods of asexual reproduction in plants with suitable examples.",
                    "Describe the female reproductive system in human beings with a neat labeled diagram."
                ],
                caseStudy: [
                    {
                        context: "A student observed that a bread piece left in a container for a few days developed a white cottony growth which later turned black.",
                        questions: [
                            "What is this white cottony growth? How does it reproduce?",
                            "Why did the growth later turn black?"
                        ]
                    }
                ]
            },
            "Chapter 9": {  
                mcq: [
                    { question: "The number of pairs of autosomes in humans is:", options: ["1", "22", "23", "46"], answer: "22" },
                    { question: "Which of the following determines the sex of a child?", options: ["Autosomes", "Chromosomes from mother", "Chromosomes from father", "Cytoplasm"], answer: "Chromosomes from father" },
                    { question: "The process by which new species develop from the existing species is called:", options: ["Evolution", "Speciation", "Natural selection", "Variation"], answer: "Speciation" }
                ],
                assertionReason: [
                    { 
                        assertion: "Sex of a child is determined by the father.", 
                        reason: "A male has one X and one Y chromosome while a female has two X chromosomes.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "Acquired characters are inherited.", 
                        reason: "Only genetic variations are passed on to the next generation.",
                        answer: "A is false but R is true."
                    }
                ],
                veryShort: [
                    "What is a gene?",
                    "Name the scientist who proposed the theory of natural selection."
                ],
                short: [
                    "How do Mendel's experiments show that traits may be dominant or recessive?",
                    "What is speciation? List four factors that could lead to speciation."
                ],
                long: [
                    "Explain Darwin's theory of evolution. How does it differ from Lamarck's theory?",
                    "What are homologous and analogous organs? Explain with examples."
                ],
                caseStudy: [
                    {
                        context: "In an experiment, Mendel crossed a tall pea plant with a dwarf pea plant. All the F1 progeny were tall.",
                        questions: [
                            "What can be inferred about the tallness trait from this observation?",
                            "What would be the phenotypic ratio if F1 plants are self-pollinated?"
                        ]
                    }
                ]
            },
            "Chapter 10": {  
                mcq: [
                    { question: "The refractive index of glass is 1.5. What is the speed of light in glass?", options: ["2 × 10^8 m/s", "3 × 10^8 m/s", "1.5 × 10^8 m/s", "2 × 10^8 m/s"], answer: "2 × 10^8 m/s" },
                    { question: "The image formed by a concave mirror is virtual, erect and larger than the object. The position of the object is:", options: ["At focus", "Between focus and pole", "Between focus and center", "Beyond center"], answer: "Between focus and pole" },
                    { question: "The power of a lens is +2.0 D. Its focal length is:", options: ["+50 cm", "+20 cm", "-50 cm", "-20 cm"], answer: "+50 cm" }
                ],
                assertionReason: [
                    { 
                        assertion: "A convex lens can form both real and virtual images.", 
                        reason: "The nature of image depends on the position of the object.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "The refractive index of diamond is very high.", 
                        reason: "Diamond has a high optical density.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    }
                ],
                veryShort: [
                    "Define 1 dioptre of power of a lens.",
                    "Name the type of mirror used in solar furnaces."
                ],
                short: [
                    "Why does a ray of light bend when it travels from one medium to another?",
                    "An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image."
                ],
                long: [
                    "With the help of a ray diagram, explain the formation of image by a concave mirror when the object is placed (i) at the center of curvature (ii) between focus and pole.",
                    "What is meant by power of accommodation of the eye? How does it help in seeing nearby and distant objects clearly?"
                ],
                caseStudy: [
                    {
                        context: "A student focused the image of a candle flame on a white screen using a convex lens. He noted down the positions of the candle, lens and screen as under: Position of candle = 12.0 cm, Position of lens = 50.0 cm, Position of screen = 88.0 cm",
                        questions: [
                            "What is the focal length of the convex lens?",
                            "Where should the candle be placed to get a diminished image on the screen?"
                        ]
                    }
                ]
            },
            "Chapter 11": {  
                mcq: [
                    { question: "The defect of vision in which a person cannot see distant objects clearly is called:", options: ["Myopia", "Hypermetropia", "Presbyopia", "Astigmatism"], answer: "Myopia" },
                    { question: "The color of the sky appears blue due to:", options: ["Reflection of light", "Refraction of light", "Dispersion of light", "Scattering of light"], answer: "Scattering of light" },
                    { question: "The persistence of vision for human eye is:", options: ["1/10th of a second", "1/16th of a second", "1/20th of a second", "1/25th of a second"], answer: "1/16th of a second" }
                ],
                assertionReason: [
                    { 
                        assertion: "The stars appear to twinkle while the planets do not.", 
                        reason: "Stars are point sources while planets have appreciable size.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "The sun appears reddish at sunrise and sunset.", 
                        reason: "At these times, the light has to travel a greater distance through the atmosphere.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    }
                ],
                veryShort: [
                    "What is the far point of a normal eye?",
                    "Name the part of the eye that controls the amount of light entering the eye."
                ],
                short: [
                    "Why does the sky appear dark instead of blue to an astronaut?",
                    "Explain the structure and function of the human eye with a neat labeled diagram."
                ],
                long: [
                    "What is myopia? How can it be corrected? Explain with a ray diagram.",
                    "Explain the phenomenon of dispersion of white light through a glass prism."
                ],
                caseStudy: [
                    {
                        context: "A person cannot see objects clearly beyond 2 m. He is advised to use spectacles.",
                        questions: [
                            "What is the defect of vision he is suffering from?",
                            "What type of lens should be used to correct this defect?"
                        ]
                    }
                ]
            },
            "Chapter 12": {  
                mcq: [
                    { question: "The SI unit of electric current is:", options: ["Volt", "Ampere", "Ohm", "Watt"], answer: "Ampere" },
                    { question: "The resistance of a conductor is directly proportional to its:", options: ["Area of cross-section", "Length", "Temperature", "None of these"], answer: "Length" },
                    { question: "Which of the following represents Ohm's law?", options: ["V = IR", "I = VR", "R = VI", "V = I/R"], answer: "V = IR" }
                ],
                assertionReason: [
                    { 
                        assertion: "The resistance of a wire increases with increase in temperature.", 
                        reason: "With increase in temperature, the number of collisions of electrons with atoms increases.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "A voltmeter is always connected in parallel across the points between which the potential difference is to be measured.", 
                        reason: "A voltmeter has a low resistance.",
                        answer: "A is true but R is false."
                    }
                ],
                veryShort: [
                    "Define 1 ohm resistance.",
                    "Name the device used to measure potential difference between two points."
                ],
                short: [
                    "What is meant by saying that the potential difference between two points is 1 V?",
                    "On what factors does the resistance of a conductor depend?"
                ],
                long: [
                    "State Ohm's law. Draw a circuit diagram to verify this law in the laboratory. How would you show graphically the relation between potential difference and current?",
                    "What is Joule's heating effect of current? Derive the expression for the heat produced."
                ],
                caseStudy: [
                    {
                        context: "An electric lamp rated 100 W is used for 5 hours daily and four electric fans rated 110 W each are used for 10 hours daily.",
                        questions: [
                            "Calculate the energy consumed by the lamp and fans in 30 days.",
                            "What would be the cost of using them for 30 days at the rate of ₹5 per unit?"
                        ]
                    }
                ]
            },
            "Chapter 13": {  
                mcq: [
                    { question: "The device used for producing electric current is called a:", options: ["Generator", "Galvanometer", "Ammeter", "Motor"], answer: "Generator" },
                    { question: "The direction of induced current is given by:", options: ["Fleming's left hand rule", "Fleming's right hand rule", "Maxwell's corkscrew rule", "Right hand thumb rule"], answer: "Fleming's right hand rule" },
                    { question: "The most important safety method used for protecting home appliances from short circuiting or overloading is:", options: ["Earthing", "Use of fuse", "Use of stabilizers", "Use of electric meter"], answer: "Use of fuse" }
                ],
                assertionReason: [
                    { 
                        assertion: "A current carrying conductor experiences a force in a magnetic field.", 
                        reason: "The magnetic field interacts with the magnetic field produced by the current in the conductor.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "The split ring in a DC motor acts as a commutator.", 
                        reason: "It reverses the direction of current in the armature coil.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    }
                ],
                veryShort: [
                    "What is the function of brushes in an electric generator?",
                    "Name the device which converts mechanical energy into electrical energy."
                ],
                short: [
                    "What is the principle of an electric motor?",
                    "Explain the working of an AC generator with a neat diagram."
                ],
                long: [
                    "Explain the phenomenon of electromagnetic induction. Describe an experiment to demonstrate it.",
                    "What is a short circuit? How does a fuse help in case of short circuiting?"
                ],
                caseStudy: [
                    {
                        context: "A student set up an experiment to demonstrate electromagnetic induction. He moved a bar magnet quickly towards a coil connected to a galvanometer.",
                        questions: [
                            "What would be the observation in the galvanometer?",
                            "What happens if the magnet is moved away from the coil?"
                        ]
                    }
                ]
            },
            "Chapter 14": {  
                mcq: [
                    { question: "Which of the following is a non-renewable source of energy?", options: ["Wind", "Solar", "Coal", "Tidal"], answer: "Coal" },
                    { question: "The major component of biogas is:", options: ["Methane", "Carbon dioxide", "Hydrogen", "Nitrogen"], answer: "Methane" },
                    { question: "The main constituent of CNG is:", options: ["Butane", "Propane", "Ethane", "Methane"], answer: "Methane" }
                ],
                assertionReason: [
                    { 
                        assertion: "Fossil fuels are non-renewable sources of energy.", 
                        reason: "They take millions of years to form and reserves are being depleted much faster than new ones are being formed.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "Solar energy is considered an environment-friendly source of energy.", 
                        reason: "Solar energy does not produce any pollution.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    }
                ],
                veryShort: [
                    "What is the main constituent of coal gas?",
                    "Name any two elements that are used in fabricating solar cells."
                ],
                short: [
                    "What are the advantages of nuclear energy?",
                    "What are the limitations of extracting energy from (i) the wind (ii) waves"
                ],
                long: [
                    "Compare and contrast fossil fuels and solar energy as sources of energy.",
                    "What is geothermal energy? Explain how it is harnessed to generate electricity."
                ],
                caseStudy: [
                    {
                        context: "In a village, people were using wood as fuel for cooking. A social worker suggested them to use biogas instead of wood.",
                        questions: [
                            "List two advantages of using biogas over wood.",
                            "Name the major component of biogas and write its chemical formula."
                        ]
                    }
                ]
            },
            "Chapter 15": {  
                mcq: [
                    { question: "Which of the following is not a greenhouse gas?", options: ["Carbon dioxide", "Methane", "Oxygen", "Chlorofluorocarbon"], answer: "Oxygen" },
                    { question: "The process of accumulation of harmful chemicals at each trophic level is called:", options: ["Biodegradation", "Biomagnification", "Bioaccumulation", "Bioremediation"], answer: "Biomagnification" },
                    { question: "The ozone layer protects us from:", options: ["Infrared rays", "Ultraviolet rays", "Gamma rays", "X-rays"], answer: "Ultraviolet rays" }
                ],
                assertionReason: [
                    { 
                        assertion: "Disposable plastic cups should not be used.", 
                        reason: "Plastic is non-biodegradable and causes environmental pollution.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "Ozone layer depletion is a serious environmental concern.", 
                        reason: "Ozone layer filters out harmful UV radiations from the sun.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    }
                ],
                veryShort: [
                    "What is the full form of CFC?",
                    "Name any two biodegradable wastes."
                ],
                short: [
                    "Why are some substances biodegradable and some non-biodegradable?",
                    "What are trophic levels? Give an example of a food chain."
                ],
                long: [
                    "Explain the phenomenon of biological magnification with the help of an example.",
                    "What is ozone layer? How is it formed? State its importance."
                ],
                caseStudy: [
                    {
                        context: "A farmer was using excessive amounts of pesticides in his fields. A scientist advised him to reduce the use of pesticides.",
                        questions: [
                            "Why was the farmer advised to reduce the use of pesticides?",
                            "What alternative method can the farmer use to protect his crops from pests?"
                        ]
                    }
                ]
            },
            "Chapter 16": {  
                mcq: [
                    { question: "Which of the following is not a natural resource?", options: ["Soil", "Water", "Electricity", "Forests"], answer: "Electricity" },
                    { question: "The most appropriate definition of a natural resource is:", options: ["Anything found in nature", "Anything found in nature that can be used by people", "Anything found in nature that has economic value", "Anything found in nature that is essential for life"], answer: "Anything found in nature that can be used by people" },
                    { question: "The most rapidly dwindling natural resource in the world is:", options: ["Water", "Forests", "Wind", "Solar energy"], answer: "Forests" }
                ],
                assertionReason: [
                    { 
                        assertion: "Sustainable management of natural resources is necessary.", 
                        reason: "Natural resources are limited and human population is growing rapidly.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    },
                    { 
                        assertion: "Water harvesting is an important method of water conservation.", 
                        reason: "It helps in recharging groundwater and prevents water runoff.",
                        answer: "Both A and R are true and R is the correct explanation of A."
                    }
                ],
                veryShort: [
                    "Name any two stakeholders of forests.",
                    "What is the main purpose of water harvesting?"
                ],
                short: [
                    "Why should we conserve forests?",
                    "List four changes you would make in your habits to become more environment-friendly."
                ],
                long: [
                    "What is watershed management? How does it help in water conservation?",
                    "Explain the concept of sustainable development with examples."
                ],
                caseStudy: [
                    {
                        context: "In a village, people were cutting down trees for fuel and timber. This led to soil erosion and scarcity of water.",
                        questions: [
                            "What alternative sources of energy can the villagers use instead of cutting trees?",
                            "How can afforestation help in solving their problems?"
                        ]
                    }
                ]
            }
        };

        function getRandomQuestions(chapters, type, count) {
            try {
                let allQuestions = [];
                chapters.forEach(chapter => {
                    if (questions[chapter] && questions[chapter][type]) {
                        allQuestions = allQuestions.concat(questions[chapter][type]);
                    }
                });
                allQuestions = allQuestions.sort(() => Math.random() - 0.5);
                return allQuestions.slice(0, count);
            } catch (error) {
                console.error("Error in getRandomQuestions:", error);
                return [];
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            startScreen.classList.add('hidden');
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        function generateAssignment() {
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                generatedPaperContainer.classList.remove('hidden');
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                // Get selected chapters
                const selectedChapters = fullPaperCheckbox.checked 
                    ? Object.keys(questions) 
                    : Array.from(document.querySelectorAll('input[name="chapter"]:checked')).map(cb => cb.value);

                if (selectedChapters.length === 0) {
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                    startContainer.classList.remove('hidden');
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                console.log("Selected chapters:", selectedChapters);

                const chapterNames = selectedChapters.map(ch => {
                    if (ch === "Full Paper") return "Full Syllabus";
                    const label = document.querySelector(`label[for="${ch.toLowerCase()}"]`);
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                console.log("Chapter names:", chapterNames);

                // Create assignment content
                let paperContent = `
                    <div class="header">
                        <h2>Class X Science Assignment</h2>
                        <h3>${selectedChapters.length === Object.keys(questions).length ? "Full Syllabus" : chapterNames}</h3>
                    </div>
                    <div class="content-area">
                        <div class="instructions">
                            <p><strong>General Instructions:</strong></p>
                            <ol>
                                <li>Complete all questions in your science notebook.</li>
                                <li>Answer all questions with proper explanations and diagrams where necessary.</li>
                                <li>Show all your workings clearly for numerical problems.</li>
                                <li>Submit the assignment by the due date.</li>
                                <li>Use blue or black ink only.</li>
                            </ol>
                        </div>
                `;

                // Get random questions
                const mcqs = getRandomQuestions(selectedChapters, 'mcq', 10);
                const assertionReasons = getRandomQuestions(selectedChapters, 'assertionReason', 5);
                const veryShort = getRandomQuestions(selectedChapters, 'veryShort', 5);
                const short = getRandomQuestions(selectedChapters, 'short', 5);
                const long = getRandomQuestions(selectedChapters, 'long', 5);
                const caseStudies = getRandomQuestions(selectedChapters, 'caseStudy', 2);

                console.log("Questions retrieved:", {
                    mcqs, assertionReasons, veryShort, short, long, caseStudies
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                let questionNumber = 1;
                
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                    <div class="question-section">
                        <h4 class="section-heading">Section A - Multiple Choice Questions (1 mark each)</h4>
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                        <div class="question">
                            <p class="question-text">${questionNumber++}. ${mcq.question}</p>
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                    </div>
                    <div class="question-section">
                        <h4 class="section-heading">Section B - Assertion Reason Questions (1 mark each)</h4>
                        <p>For each question, choose the correct option:</p>
                `;
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                    paperContent += `
                        <div class="question">
                            <p class="question-text">${questionNumber++}. <strong>Assertion (A):</strong> ${ar.assertion}</p>
                            <p class="assertion-reason"><strong>Reason (R):</strong> ${ar.reason}</p>
                            <p class="option">Options:</p>
                            <p class="option">A. Both A and R are true and R is the correct explanation of A.</p>
                            <p class="option">B. Both A and R are true but R is not the correct explanation of A.</p>
                            <p class="option">C. A is true but R is false.</p>
                            <p class="option">D. A is false but R is true.</p>
                        </div>
                    `;
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                    </div>
                    <div class="question-section">
                        <h4 class="section-heading">Section C - Very Short Answer Questions (2 marks each)</h4>
                `;
                veryShort.forEach(q => {
                    paperContent += `
                        <div class="question">
                            <p class="question-text">${questionNumber++}. ${q}</p>
                        </div>
                    `;
                });
                
                // Section D - Short Questions
                paperContent += `
                    </div>
                    <div class="question-section">
                        <h4 class="section-heading">Section D - Short Answer Questions (3 marks each)</h4>
                `;
                short.forEach(q => {
                    paperContent += `
                        <div class="question">
                            <p class="question-text">${questionNumber++}. ${q}</p>
                        </div>
                    `;
                });
                
                // Section E - Long Questions
                paperContent += `
                    </div>
                    <div class="question-section">
                        <h4 class="section-heading">Section E - Long Answer Questions (5 marks each)</h4>
                `;
                long.forEach(q => {
                    paperContent += `
                        <div class="question">
                            <p class="question-text">${questionNumber++}. ${q}</p>
                        </div>
                    `;
                });
                
                // Section F - Case Study Questions
                paperContent += `
                    </div>
                    <div class="question-section">
                        <h4 class="section-heading">Section F - Case Study Based Questions (4 marks each)</h4>
                        <p><em>Each case study has 2 questions of 2 marks each.</em></p>
                `;
                caseStudies.forEach((cs, index) => {
                    paperContent += `
                        <div class="case-study">
                            <p><strong>Case Study ${index + 1}:</strong> ${cs.context}</p>
                            ${cs.questions.map((q, qIndex) => 
                                `<div class="case-study-question">
                                    <p class="question-text">${questionNumber++}. ${q}</p>
                                </div>`
                            ).join('')}
                        </div>
                    `;
                });
                
                // Add buttons below the generated paper
                paperContent += `
                        </div>
                        <div class="action-buttons">
                            <button class="btn btn-primary" onclick="downloadPDF()">Download as PDF</button>
                            <button class="btn btn-success" onclick="window.print()">Print</button>
                            <button class="btn btn-danger" onclick="backToStart()">Back to Start</button>
                        </div>
                    </div>
                `;

                console.log("Final paper content generated");
                generatedPaperContainer.innerHTML = paperContent;
                console.log("Assignment generated successfully");

            } catch (error) {
                console.error("Error generating assignment:", error);
                alert("An error occurred while generating the assignment. Please check the console for details.");
                backToStart();
            }
        }

        async function downloadPDF() {
            const element = document.getElementById('generatedPaperContainer');
            
            // Create a temporary div with optimized settings
            const tempDiv = document.createElement('div');
            tempDiv.style.position = 'absolute';
            tempDiv.style.left = '-9999px';
            tempDiv.style.width = '794px'; // A4 width in pixels (210mm)
            tempDiv.style.backgroundColor = 'white';
            tempDiv.style.padding = '20px';
            tempDiv.innerHTML = element.innerHTML;
            document.body.appendChild(tempDiv);

            try {
                const pdf = new jsPDF('p', 'mm', 'a4');
                const pageWidth = pdf.internal.pageSize.getWidth() - 25.4; // 0.5" margins
                const pageHeight = pdf.internal.pageSize.getHeight() - 25.4;
                
                // Split content into pages
                let position = 12.7; // Start with 0.5" top margin
                let remainingHeight = tempDiv.scrollHeight;
                let pageNum = 1;
                
                while (remainingHeight > 0) {
                    // Capture the current page section
                    const canvas = await html2canvas(tempDiv, {
                        scale: 2,
                        windowHeight: pageHeight * 3.78, // mm to px
                        windowWidth: pageWidth * 3.78,
                        y: position * 3.78, // mm to px
                        height: pageHeight * 3.78,
                        useCORS: true,
                        backgroundColor: '#ffffff',
                        logging: false
                    });

                    const imgData = canvas.toDataURL('image/jpeg', 0.92);
                    
                    // Add page to PDF
                    if (pageNum > 1) {
                        pdf.addPage('a4', 'portrait');
                    }
                    
                    pdf.addImage(imgData, 'JPEG', 12.7, 12.7, pageWidth, canvas.height * pageWidth / canvas.width);
                    
                    position += pageHeight;
                    remainingHeight -= pageHeight * 3.78; // px
                    pageNum++;
                }

                // Save PDF
                pdf.save('Class_10_Science_Assignment.pdf');
                console.log("PDF saved successfully");
                
            } catch (error) {
                console.error('PDF generation error:', error);
                alert('Error generating PDF. Please check the console for details.');
                // Remove temporary div if it exists
                const tempDiv = document.querySelector('.temp-pdf-container');
                if (tempDiv) {
                    document.body.removeChild(tempDiv);
                }
            }
        }
    </script>
</body>
</html>