Exam Success Guide (Set 2: Chapters 7–12 Comprehensive)

Use these structured guidelines to maximize your performance on full-syllabus examinations:

1-Mark Questions: State key scientific terminology, exact standard units, or historical dates precisely.
2-Mark Questions: Provide crisp two-line explanations or two contrasting comparative points.
3-Mark Questions: Use itemized points with bold headers or structured step-by-step procedures.
5-Mark Questions: Break your answer into clear logical parts: definition/concept, underlying mechanism, examples, and practical/environmental significance.

SCIENCE MODEL QUESTION PAPER — SET 2

Covered Chapters: Temperature & Its Measurement, States of Water, Methods of Separation, Living Creatures, Nature's Treasures & Beyond Earth (Chapters 7 to 12)

Time Allowed: 3 Hours Maximum Marks: 100

SECTION A: Objective & Very Short Answer Questions (20 Marks)

Q1. What is the normal temperature of a healthy human body on the Fahrenheit scale?

Ans: 98.6°F

Q2. Which thermometric liquid is commonly used in laboratory thermometers due to its uniform expansion with heat?

Ans: Mercury (or Alcohol in low-temperature thermometers)

Q3. What process describes the continuous loss of water in the form of water vapor from the aerial parts of plants, mainly leaves?

Ans: Transpiration

Q4. At what temperature (in °C) under normal pressure does liquid water boil and turn into steam?

Ans: 100°C

Q5. Name the separation technique used to separate butter or cream from milk or curd by rapid spinning.

Ans: Churning (or Centrifugation)

Q6. Which physical method can be used to separate iron nails or pins mixed with sand?

Ans: Magnetic separation

Q7. What is the clear liquid called that is poured out during the decantation process after heavy solids settle?

Ans: Supernatant (or clear liquid)

Q8. What term refers to the process by which living organisms break down food using oxygen to release energy?

Ans: Respiration

Q9. Which microscopic organelle or structure is known as the basic building block of all living organisms?

Ans: Cell

Q10. Name the biological process of removing metabolic waste materials from the body of a living creature.

Ans: Excretion

Q11. State whether sunlight is a renewable or non-renewable natural resource.

Ans: Renewable natural resource

Q12. What is the approximate percentage of nitrogen gas present in Earth's atmosphere?

Ans: 78%

Q13. Name the natural fossil fuel formed from buried prehistoric plant vegetation over millions of years.

Ans: Coal

Q14. Which constellation is popularly known in India as the Saptarishi?

Ans: Ursa Major (or the Big Dipper)

Q15. Name the prominent constellation that resembles a hunter holding a shield and a club.

Ans: Orion

Q16. What unit represents the average distance between the Earth and the Sun (~150 million kilometers)?

Ans: Astronomical Unit (au)

Q17. Which planet is the largest planet in our solar system?

Ans: Jupiter

Q18. What celestial bodies are commonly called "dirty snowballs" made of ice, dust, and rock that form glowing tails near the Sun?

Ans: Comets

Q19. Name India's space agency responsible for missions like Chandrayaan and Mangalyaan.

Ans: ISRO (Indian Space Research Organisation)

Q20. In which Indian Union Territory is the Hanle Dark Sky Reserve located?

Ans: Ladakh

SECTION B: Short Answer Questions (20 Marks)

Q21. Why should a clinical thermometer be jerked before measuring body temperature?

1. Jerking pushes the mercury column back into the bulb past the kink.
2. It ensures the reading starts below 35°C for an accurate measurement.

Q22. How do clouds form in the upper atmosphere?

1. Evaporated water vapor rises into the atmosphere where temperatures are cooler.
2. The vapor condenses around fine dust particles into microscopic water droplets, combining to form clouds.

Q23. Why can threshing not be used to separate salt from sea water?

1. Threshing is a physical method used to separate solid grains from stalks.
2. Salt is completely dissolved in liquid sea water and requires evaporation for separation.

Q24. Distinguish between a solute and a solvent using a sugar-water solution as an example.

1. Solute: The substance that dissolves in a liquid (e.g., Sugar).
2. Solvent: The liquid in which the solute dissolves (e.g., Water).

Q25. How do plants respond to the stimulus of light (phototropism)?

1. Plant shoots naturally bend and grow towards the direction of incoming sunlight.
2. This growth movement ensures leaves receive maximum light for photosynthesis.

Q26. Why are green plants called primary producers in an ecosystem?

1. Green plants synthesize their own food from water and carbon dioxide using sunlight (photosynthesis).
2. All animals and humans depend directly or indirectly on plants for energy and food.

Q27. Why are fossil fuels classified as non-renewable natural resources?

1. Fossil fuels take millions of years to form under extreme temperature and pressure conditions beneath the Earth.
2. Their current rate of consumption far exceeds their formation rate, leading to permanent depletion.

Q28. Why does Venus experience extremely high surface temperatures even though Mercury is closer to the Sun?

1. Venus has a thick atmosphere composed predominantly of carbon dioxide gas.
2. This dense atmospheric cover traps solar heat through an extreme greenhouse effect.

Q29. What is the asteroid belt and where is it located in our solar system?

1. The asteroid belt is a circumstellar disc populated by numerous irregular rocky objects called asteroids.
2. It is situated in the region between the orbits of Mars and Jupiter.

Q30. State two primary objectives of establishing dark sky reserves near astronomical observatories.

1. To minimize artificial light pollution so celestial bodies can be clearly observed.
2. To preserve pristine night skies for scientific astronomical research and eco-tourism.

SECTION C: Medium Answer Questions (30 Marks)

Q31. Explain why air is considered a mixture and list its major components along with their roles.

Reason for Mixture: Air consists of various gases physically mixed together without fixed chemical proportions.
Nitrogen (78%): Controls combustion and supports essential nutrient cycles for plant growth.
Oxygen (21%): Vital for cellular respiration in living organisms and for burning processes.
Carbon Dioxide & Traces (1%): Used by plants for photosynthesis and helps retain thermal warmth on Earth.

Q32. Describe the water cycle and explain how human activities disrupt its natural balance.

Cycle Mechanism: Continuous circulation through solar evaporation, atmospheric condensation into clouds, and rainfall precipitation.
Deforestation Impact: Cutting trees reduces plant transpiration, reducing cloud formation and regional rainfall.
Urbanization & Pollution: Paving ground surfaces prevents groundwater recharge, while industrial emissions contaminate rainwater.

Q33. Outline a laboratory procedure to obtain pure salt and clean water from a salt-water solution.

Evaporation Stage: Heat the salt-water mixture in a covered vessel; water turns into vapor, leaving solid salt behind.
Condensation Stage: Direct the escaping steam through a cooled tube or against a cold surface.
Collection: Condensed steam turns back into clean liquid water, successfully separating dissolved salt and pure water.

Q34. Compare living organisms and non-living objects across three structural and functional parameters.

Cellular Structure: Living organisms consist of functional cells; non-living things lack cellular organization.
Metabolism & Respiration: Living beings take in nutrients, respire, and excrete waste; non-living objects perform no metabolic processes.
Growth & Reproduction: Living things grow internally and reproduce offspring; non-living things grow only by external accretion and cannot reproduce.

Q35. Explain the importance of topsoil and discuss two causes and two preventive measures of soil erosion.

Importance: Topsoil is rich in humus and mineral nutrients essential for plant growth and agricultural yields.
Causes of Erosion: Heavy rain runoff washing away bare soil, and strong winds sweeping loose soil off deforested land.
Preventive Measures: Planting vegetation/trees (afforestation) to anchor soil, and practicing terrace farming on slopes.

Q36. Discuss how temperature affects the states of matter with specific reference to ice, water, and steam.

Melting (Solid to Liquid): Heating ice above 0°C increases particle movement, converting solid ice into liquid water.
Boiling/Evaporation (Liquid to Gas): Further heating water to 100°C turns liquid water into gaseous steam.
Reversibility: Cooling steam condenses it back into water, and cooling water below 0°C freezes it back into solid ice.

Q37. Describe the main physical differences between inner (terrestrial) planets and outer (gas giant) planets.

Inner Planets (Mercury, Venus, Earth, Mars): Small, dense, solid rocky surfaces, located close to the Sun with few or no moons.
Outer Planets (Jupiter, Saturn, Uranus, Neptune): Massive size, composed mostly of hydrogen, helium, and ice, with deep gaseous atmospheres and numerous moons.
Ring Systems: Outer planets possess distinct ring systems, whereas inner planets have none.

Q38. How can the constellation Ursa Major be used to locate the Pole Star in the night sky?

Identify the Bowl: Locate the seven bright stars of Ursa Major (Saptarishi) forming a bowl with a handle.
Pointer Stars: Identify the two stars at the outer edge of the bowl opposite the handle.
Project Line: Draw an imaginary straight line extending through these two pointer stars towards the north.
Locate Dhruva Tārā: The line leads directly to a moderately bright star standing fixed in the northern sky—the Pole Star.

Q39. Write a note on the Chandrayaan-3 mission, highlighting its key components and historical significance.

Mission Components: Consisted of a propulsion module, the Vikram lander, and the Pragyan rover.
Historic Touchdown: Successfully performed a soft landing near the Moon's unexplored south pole on 23 August 2023.
Scientific Milestone: Positioned India as the 4th nation to soft-land on the Moon and the 1st to reach the lunar south polar region.

Q40. Explain what a light year is and why conventional units like kilometers are inconvenient for interstellar distances.

Definition: A light year is the total distance traveled by light in one year in a vacuum (~9.46 trillion km).
Astronomical Scale: Celestial bodies are separated by immense distances across deep space.
Inconvenience of Kilometers: Using kilometers results in unwieldy numbers with dozens of zeros, making light years a far more practical unit.

SECTION D: Long Answer Questions (30 Marks)

Q41. Detail the construction, working, reading method, and clinical precautions of a mercury clinical thermometer.

Construction: A sealed narrow glass tube with a mercury-filled bulb at one end and a safety kink in the capillary tube.
Working Mechanism: Body heat causes mercury in the bulb to expand along the graduated Celsius/Fahrenheit scale.
Function of Kink: Prevents mercury from flowing back into the bulb automatically when removed from the body, allowing accurate reading.
Precautions: Wash with antiseptic before/after use, jerk down below 35°C, handle carefully, and never hold by the bulb while reading.

Q42. Describe a step-by-step scheme to separate a complex mixture containing sand, common salt, and iron filings into its individual pure components.

Step 1 (Magnetic Separation): Pass a magnet through the dry mixture to attract and remove all iron filings.
Step 2 (Dissolution): Add water to the remaining sand and salt mixture; stir thoroughly so the salt dissolves completely while sand remains solid.
Step 3 (Filtration): Pour the mixture through filter paper in a funnel. Insoluble sand remains on the filter paper as residue; clear salt solution passes through as filtrate.
Step 4 (Evaporation): Heat the clear filtrate liquid until all water vaporizes, leaving pure dry salt crystals behind.

Q43. Describe how life on Earth depends on natural cycles, focusing on the carbon-oxygen cycle and the role of soil and forests.

Photosynthesis & Respiration: Plants absorb atmospheric CO₂ and release O₂ during photosynthesis; animals consume O₂ and exhale CO₂ during respiration, keeping gas levels balanced.
Forest Ecological Role: Forests act as carbon sinks, purify atmospheric air, influence monsoon rains, and provide wildlife habitats.
Soil Ecosystem: Soil anchors plants, stores water, decomposes organic matter, and cycles nutrients back into food chains.
Human Responsibility: Protecting green cover and preventing pollution are essential to preserving these life-sustaining cycles.

Q44. Discuss life processes in living organisms, explaining how nutrition, respiration, excretion, and reproduction work together to sustain life.

Nutrition: Intake of food materials to provide organic matter and chemical energy for cellular activities.
Respiration: Chemical breakdown of nutrients using oxygen inside cells to yield biological energy (ATP).
Excretion: Removal of metabolic waste products to maintain internal biochemical balance and prevent cellular toxicity.
Reproduction: Production of new individuals to ensure species survival across generations.
Interdependence: These processes operate in sync to maintain health, growth, and survival in living creatures.

Q45. Analyze the causes and consequences of environmental degradation (water pollution, air pollution, deforestation) and propose solutions aligned with sustainable development.

Causes of Degradation: Industrial effluent discharge, excessive vehicular emissions, indiscriminate logging, and plastic waste accumulation.
Consequences: Severe water scarcity, respiratory diseases, loss of wildlife habitats, soil erosion, and climate change.
Sustainable Solutions: Widespread adoption of renewable solar/wind energy, rainwater harvesting infrastructure, strict industrial waste treatment, and massive tree-planting drives.
Individual Action: Practicing the 3 Rs (Reduce, Reuse, Recycle) and conserving energy in daily life.

Q46. Explain the solar system, detail the unique features that make Earth habitable, and outline humanity's astronomical exploration from ancient skywatching to modern space probes.

Solar System Structure: The Sun at the center with eight planets, dwarf planets, moons, asteroids, and comets revolving in predictable orbits.
Earth's Habitability: Ideal distance from the Sun (goldilocks zone), liquid water availability, protective atmospheric ozone layer, and suitable oxygen levels.
Ancient Exploration: Skywatching, constellation mapping, and using star movements for agricultural calendars and sea navigation.
Modern Space Exploration: Telescopes, dark sky reserves (e.g., Hanle), satellite technology, and interplanetary missions like ISRO's Chandrayaan and Mangalyaan expanding our understanding of the universe.