Science in Class 7 explains everyday observations through experiments, evidence, diagrams, and reasoning. A good science answer states the concept first, then supports it with an observation, example, or result.
Class 7 Science in the 2026-27 NCERT textbook Curiosity trains students to observe, test, record, and explain ideas from daily life. The book covers acids and bases, circuits, metals and non-metals, physical and chemical changes, adolescence, heat transfer, motion, life processes, light, and the Earth-Moon-Sun system. Important Questions Class 7 Science gives students a structured way to revise these topics through solved questions. The answers explain the reason behind each observation, which helps students prepare for CBSE school exams in 2026.
Key Takeaways
- Curiosity 2026-27: Class 7 Science has 12 chapters across physics, chemistry, biology, and earth science.
- Activity-Based Learning: The textbook uses experiments, observations, illustrations, puzzles, and projects.
- Exam Practice: Students should revise definitions, diagrams, experiments, reasoning, and applications.
- Scientific Method: Strong answers use observation, evidence, correct terms, examples, and clear conclusions.
Important Questions Class 7 Science Structure 2026
| Area |
Main Chapters |
Practice Focus |
| Chemistry |
Acids, bases, metals, non-metals, physical and chemical changes |
Tests, reactions, properties, examples |
| Physics |
Circuits, heat transfer, time, motion, light, shadows, reflections |
Diagrams, reasoning, observations |
| Biology and Earth Science |
Adolescence, life processes, Earth, Moon, Sun |
Functions, processes, labelled diagrams, applications |
Class 7 Science Important Questions With Answers From Curiosity
These Class 7 Science Important Questions With Answers follow the new NCERT Curiosity textbook pattern. The questions move in one continuous sequence and include concepts, activities, observations, diagrams, and reasoning.
1. What does science mean in the Class 7 Curiosity textbook?
Science means observing, asking questions, testing ideas, and explaining the world through evidence.
The textbook presents science as a process. Students learn by observing changes, asking why they happen, testing possible answers, and discussing results.
For example, a rusted iron gate can lead to questions about air, moisture, metals, and chemical changes.
Answer: Science is a method of observing, questioning, experimenting, and explaining natural events.
2. Why is The Ever-Evolving World of Science important in Class 7?
The chapter shows that science grows through curiosity, observation, and new discoveries.
It connects the rest of the textbook by showing how scientific ideas develop. Students learn that science needs careful observation and open thinking.
This chapter builds the habit of asking better questions before studying experiments and concepts.
Answer: It introduces science as an evolving process based on evidence and enquiry.
3. What is an acid?
An acid is a substance that usually tastes sour and turns blue litmus red.
Lemon juice, vinegar, curd, and tamarind water contain acids. Students should use indicators to test substances because tasting unknown materials can be unsafe.
Litmus paper gives quick evidence during an acid-base activity.
Answer: An acid turns blue litmus red and is present in substances like lemon juice and vinegar.
4. What is a base?
A base is a substance that usually feels soapy and turns red litmus blue.
Soap solution, baking soda solution, and lime water show basic nature. Bases may feel slippery, but students should avoid touching unknown solutions directly.
Indicators help students identify bases safely during experiments.
Answer: A base turns red litmus blue and can feel slippery or soapy.
5. What is a neutral substance?
A neutral substance is neither acidic nor basic.
Neutral substances usually show no colour change with red or blue litmus. Pure water is a common example.
A neutral result means the substance does not show acidic or basic behaviour in that test.
Answer: A neutral substance shows neither acidic nor basic character.
6. How does litmus paper identify acids and bases?
Litmus paper identifies acids and bases through colour change.
- Blue litmus turns red in an acid.
- Red litmus turns blue in a base.
- Neutral substances usually show no change.
Students should record the original colour, final colour, and conclusion.
Answer: Acids turn blue litmus red, while bases turn red litmus blue.
7. Why should students use indicators instead of tasting substances?
Students should use indicators because unknown substances can harm the body.
Some acids and bases can irritate skin, eyes, and mouth. Indicators such as litmus give safer evidence.
Good science values safe observation over guessing.
Answer: Indicators identify acids and bases safely without tasting the substance.
8. What is an electric circuit?
An electric circuit is a complete path through which electric current flows.
A simple circuit has a cell, wires, switch, and bulb. When the path is complete, current flows and the bulb glows.
If the path breaks at any point, current stops flowing.
Answer: An electric circuit is a closed path for electric current.
9. Why does a bulb glow in a closed circuit?
A bulb glows because electric current flows through it in a closed circuit.
The cell provides energy, and the wires carry current. The bulb converts electrical energy into light and heat.
A loose wire, weak cell, open switch, or damaged bulb can stop the glow.
Answer: A bulb glows when current flows through a complete circuit.
10. What is the function of a switch in a circuit?
A switch controls the flow of electric current by opening or closing the circuit.
When the switch is ON, it completes the circuit. When the switch is OFF, it creates a gap.
Switches help control bulbs, fans, bells, and many devices.
Answer: A switch opens or closes a circuit to control current flow.
11. Why should wet hands avoid electrical switches?
Wet hands increase the risk of electric shock.
Water with dissolved salts can conduct electricity. If current passes through the body, it can cause injury.
Students should touch switches only with dry hands.
Answer: Wet hands can conduct electricity and cause electric shock.
12. What are metals?
Metals are materials that are usually hard, shiny, malleable, ductile, and good conductors.
Iron, copper, aluminium, silver, and gold are common metals. Copper conducts electricity well, while aluminium conducts heat and stays light.
Metals are used in wires, utensils, machines, tools, and vehicles.
Answer: Metals are shiny, strong materials that conduct heat and electricity.
13. What are non-metals?
Non-metals are materials that usually lack metallic lustre and conduct poorly.
Sulphur, carbon, oxygen, and phosphorus are examples. Many solid non-metals are brittle and break when hammered.
Some non-metals are essential for life, such as oxygen.
Answer: Non-metals usually lack metallic properties and are poor conductors.
14. Why is copper used for electric wires?
Copper is used for electric wires because it conducts electricity well and is ductile.
Ductility means a material can be drawn into thin wires. Copper allows current to pass easily through circuits.
This makes it useful in household wiring and electrical appliances.
Answer: Copper conducts electricity well and can be drawn into wires.
15. Why is aluminium used for cooking vessels?
Aluminium is used for cooking vessels because it is light and conducts heat well.
Good heat conduction helps food cook evenly. Its low weight makes utensils easy to handle.
Aluminium also resists rust better than iron in many conditions.
Answer: Aluminium is light and spreads heat efficiently during cooking.
Class 7 Science Extra Questions From Chemistry And Changes
Acids, bases, metals, non-metals, and changes often appear as observation-based questions. These Class 7 Science Extra Questions help students explain colour changes, material properties, and the difference between physical and chemical changes.
16. What is a physical change?
A physical change changes the size, shape, state, or appearance of a substance.
A new substance does not form during a physical change. Melting ice, tearing paper, folding cloth, and dissolving sugar in water are examples.
The material remains the same, even when its form changes.
Answer: A physical change changes form or state without forming a new substance.
17. What is a chemical change?
A chemical change forms one or more new substances.
Burning paper, rusting iron, curd formation, and cooking food are examples. These changes often show colour change, gas formation, smell, heat, light, or precipitate formation.
A chemical change gives products with new properties.
Answer: A chemical change forms new substances with new properties.
18. Why is rusting of iron a chemical change?
Rusting is a chemical change because iron forms a new substance called rust.
Rust forms when iron reacts with oxygen and moisture. Rust has a reddish-brown colour and different properties from iron.
Paint, oil, and galvanisation can reduce rusting.
Answer: Rusting forms a new substance, so it is a chemical change.
19. Is melting of ice a physical change?
Melting of ice is a physical change because only the state changes.
Ice changes from solid water to liquid water. No new substance forms.
The water can freeze again when cooled.
Answer: Melting of ice is a physical change.
20. Why is burning of paper a chemical change?
Burning paper is a chemical change because ash, smoke, and gases form.
The original paper changes into new substances. These products have different properties from paper.
Paper cannot be obtained back by simple cooling.
Answer: Burning paper forms new substances and is a chemical change.
21. Why is curd formation from milk a chemical change?
Curd formation is a chemical change because milk changes into a new substance.
Curd has a different taste, smell, and texture from milk. Microorganisms help this change happen.
The original milk cannot be obtained back by a simple physical process.
Answer: Curd formation produces a new substance, so it is a chemical change.
22. How can students identify a chemical change during an activity?
Students can identify a chemical change by observing evidence of new substance formation.
- A new colour may appear.
- A gas may form.
- Heat or light may release.
- A new smell or solid may appear.
These clues help students identify the result correctly.
Answer: A chemical change shows signs such as gas, colour change, heat, smell, or new solid formation.
Class 7 Science Questions With Answers On Growth, Heat And Motion
Growth, heat, and motion need clear examples from daily life. These Class 7 Science Questions With Answers help students explain body changes, heat transfer, measurements, and speed.
23. What is adolescence?
Adolescence is the stage of growth between childhood and adulthood.
During adolescence, the body grows quickly. Physical, emotional, and mental changes occur due to hormones.
Students should understand this stage scientifically and respectfully.
Answer: Adolescence is the stage when a child’s body begins to mature into an adult body.
24. Why is balanced nutrition important during adolescence?
Balanced nutrition supports rapid growth during adolescence.
The body needs proteins, carbohydrates, fats, vitamins, minerals, and water. Iron supports blood, while calcium supports bones and teeth.
A poor diet can affect growth, strength, concentration, and health.
Answer: Balanced nutrition supports growth, energy, bones, blood, and overall health.
25. Why is personal hygiene important during adolescence?
Personal hygiene helps maintain health during adolescence.
Sweat and oil secretion may increase during this stage. Regular bathing, clean clothes, and menstrual hygiene can prevent infections and body odour.
Hygiene builds comfort, confidence, and health.
Answer: Personal hygiene helps prevent infections and supports good health.
26. What is heat transfer?
Heat transfer is the movement of heat from a hotter body to a colder body.
Heat moves through conduction, convection, and radiation. A hot cup warms a metal spoon through conduction.
Heat transfer explains cooking, clothing, weather, and many household examples.
Answer: Heat transfer is the movement of heat from hot regions to cold regions.
27. What is conduction?
Conduction is heat transfer through direct contact between particles.
It occurs mainly in solids. When one end of a metal rod is heated, heat reaches the other end through particle-to-particle transfer.
Metals conduct heat well, while wood and plastic conduct heat poorly.
Answer: Conduction transfers heat through direct contact.
28. What is convection?
Convection is heat transfer through the movement of liquids or gases.
When water is heated, hot water rises and cooler water sinks. This movement creates convection currents.
Convection helps explain boiling water, sea breeze, land breeze, and air movement.
Answer: Convection transfers heat through moving fluids.
29. What is radiation?
Radiation is heat transfer that does not need a medium.
The Sun’s heat reaches Earth through radiation. Heat from a fire can also reach us from a distance.
Radiation can travel through empty space.
Answer: Radiation transfers heat without requiring a material medium.
30. Why do woollen clothes keep us warm?
Woollen clothes keep us warm because wool traps air.
Air is a poor conductor of heat. The trapped air reduces heat loss from the body.
This helps the body stay warm during winter.
Answer: Woollen clothes reduce heat loss by trapping air.
31. What is motion?
Motion is the change in position of an object with time.
A moving bus, a running child, a falling leaf, and a rotating fan show motion. Motion can be straight, circular, periodic, fast, or slow.
To describe motion, students should mention position and time.
Answer: Motion means change in position with time.
32. What is speed?
Speed tells how fast an object moves.
Formula:
Speed = Distance / Time
If a cyclist covers 60 km in 3 hours, then:
Speed = 60 / 3 = 20 km/h
Answer: Speed is distance travelled per unit time.
33. A car travels 120 km in 3 hours. Find its speed.
The speed of the car is 40 km/h.
Given Data:
- Distance = 120 km
- Time = 3 h
Formula Used:
Speed = Distance / Time
Calculation:
Speed = 120 / 3
Speed = 40 km/h
Answer: 40 km/h
34. Why do we use standard units in science?
Standard units make measurements uniform and reliable.
If students used different local units, results would become confusing. Standard units such as metre, kilogram, second, and degree Celsius allow comparison.
Science needs measurements that others can repeat.
Answer: Standard units help everyone measure and compare quantities in the same way.
NCERT Class 7 Science Important Questions On Life Processes, Light And Space
The new NCERT book connects living systems with observations from daily life and the sky. These NCERT Class 7 Science Important Questions focus on processes, diagrams, light behaviour, and the Earth-Moon-Sun system.
35. What are life processes?
Life processes are activities that living organisms perform to stay alive.
They include nutrition, respiration, transport, excretion, growth, and reproduction. Plants and animals perform these processes in different ways.
For example, animals eat food, while green plants make food using sunlight.
Answer: Life processes are essential activities that maintain life.
36. Why do animals need food?
Animals need food for energy, growth, repair, and body functions.
Food gives energy for movement, breathing, digestion, and daily activities. It also provides materials for growth and healing.
Different animals have different food habits because their body structures and habitats differ.
Answer: Animals need food for energy, growth, repair, and survival.
37. What is digestion?
Digestion is the process of breaking food into simpler substances.
The body can absorb simpler substances and use them for energy and growth. Digestion begins in the mouth and continues in different organs.
Chewing, saliva, stomach juices, and intestinal enzymes help digestion.
Answer: Digestion breaks complex food into simpler absorbable substances.
38. Why do plants need leaves?
Plants need leaves mainly for photosynthesis.
Leaves contain chlorophyll, which helps plants use sunlight to make food. Leaves also allow gas exchange through tiny openings called stomata.
This makes leaves essential for plant survival.
Answer: Leaves help plants make food and exchange gases.
39. What is photosynthesis?
Photosynthesis is the process by which green plants make food using sunlight, carbon dioxide, and water.
The process occurs mainly in leaves. Chlorophyll captures sunlight and helps the plant produce glucose and oxygen.
Word equation:
Carbon dioxide + Water + Sunlight → Glucose + Oxygen
Answer: Photosynthesis is the food-making process in green plants.
40. Why are plants called producers?
Plants are called producers because they make their own food.
They use sunlight, water, and carbon dioxide during photosynthesis. Animals depend directly or indirectly on plants for food.
Plants form the base of many food chains.
Answer: Plants are producers because they prepare food through photosynthesis.
41. What is a shadow?
A shadow is a dark region formed when an opaque object blocks light.
A shadow needs a light source, an opaque object, and a screen or surface. Transparent objects allow light to pass through them, so they form faint or unclear shadows.
Shadows change when the position of the light source changes.
Answer: A shadow forms when an object blocks light.
42. Why does a shadow change during the day?
A shadow changes during the day because the Sun’s apparent position changes.
Morning and evening shadows are longer. Around noon, shadows are shorter because the Sun appears higher in the sky.
This observation connects light with Earth’s rotation.
Answer: Shadows change because sunlight falls from different directions during the day.
43. What is reflection of light?
Reflection of light is the bouncing back of light from a surface.
A mirror gives clear reflection because it has a smooth surface. Rough surfaces scatter light in many directions.
Reflection helps us see objects and use mirrors.
Answer: Reflection is the bouncing back of light from a surface.
44. Why do we see our image in a mirror?
We see our image in a mirror because a smooth mirror reflects light regularly.
Light from our body falls on the mirror and returns to our eyes. The brain understands this reflected light as an image.
A polished mirror forms a clearer image than a rough wall.
Answer: A mirror forms an image through regular reflection of light.
45. Why does the Moon appear to change shape?
The Moon appears to change shape because we see different portions of its sunlit half.
The Moon does not produce its own light. It reflects sunlight.
As the Moon moves around Earth, the visible bright portion changes. These changing shapes are called phases of the Moon.
Answer: Moon phases occur because the visible sunlit part changes.
Class 7 Science Hard Questions With Answers For CBSE 2026
Observation-based questions often combine two concepts, such as indicator tests and conclusions, or conduction and material properties. These Class 7 Science Hard Questions With Answers help students practise exam-style reasoning.
46. A student tests lemon juice with blue litmus. What happens and why?
Blue litmus turns red because lemon juice is acidic.
Lemon juice contains citric acid. Acids change blue litmus to red during an indicator test.
This question checks observation and conclusion together.
Answer: Blue litmus turns red because lemon juice is acidic.
47. A bulb does not glow in a circuit. Give three possible reasons.
A bulb may fail to glow due to an open circuit, weak cell, or damaged bulb.
- The switch may be OFF.
- A wire may be loose or disconnected.
- The cell may be weak or the bulb may be fused.
Students should check each part of the circuit before writing the conclusion.
Answer: The circuit may be open, the cell may be weak, or the bulb may be damaged.
48. Why does a steel spoon feel hotter than a wooden spoon in hot tea?
A steel spoon feels hotter because steel conducts heat faster than wood.
Metals are good conductors of heat. Wood is a poor conductor, so heat moves slowly through it.
This is why many cooking utensils have wooden or plastic handles.
Answer: Steel conducts heat faster than wood.
49. Why do astronauts need sunlight or artificial light to see objects on the Moon?
Astronauts need light because objects become visible when light reaches the eyes.
The Moon has no light of its own. It reflects sunlight. In dark areas, artificial light helps astronauts see objects.
This links reflection with space observations.
Answer: Objects become visible when light reflects from them into the eyes.
50. A student says all shiny materials are metals. Is this correct?
This is incorrect because lustre alone cannot identify a metal.
Some non-metals can appear shiny in certain forms. A material should also be checked for conductivity, malleability, ductility, and hardness.
Science uses more than one property for classification.
Answer: Lustre alone cannot prove that a material is a metal.
Class 7 Science Activity Based Questions For Experiments And Observations
Activity-based questions in the Curiosity textbook ask students to connect the observation with the reason. Class 7 Science Activity Based Questions often come from litmus tests, circuits, rusting, heat transfer, and shadows.
51. What should a student conclude if blue litmus turns red in a solution?
The solution is acidic because acids turn blue litmus red.
The colour change is the observation. The acidic nature is the conclusion.
This answer should mention both the test and the result.
Answer: The solution is acidic.
52. What should a student conclude if red litmus turns blue in a solution?
The solution is basic because bases turn red litmus blue.
The indicator gives evidence for the nature of the solution. Soap solution and baking soda solution can show this result.
Students should avoid guessing by smell or touch.
Answer: The solution is basic.
53. Why does an open switch stop a bulb from glowing?
An open switch breaks the circuit and stops current flow.
A bulb glows only when the circuit is complete. An open switch creates a gap in the conducting path.
This is a common circuit observation question.
Answer: An open switch stops the bulb because the circuit becomes incomplete.
54. What observation shows that rusting needs moisture?
Iron rusts faster in moist air than in dry air.
Moisture helps iron react with oxygen. Dry conditions slow down rusting.
This observation explains why iron objects rust quickly during rainy weather.
Answer: Faster rusting in moist air shows that rusting needs moisture.
55. Why does a shadow become shorter near noon?
A shadow becomes shorter near noon because the Sun appears higher in the sky.
Sunlight falls more vertically at noon. The object blocks light over a smaller ground area.
This observation links shadows with the Sun’s position.
Answer: A shadow becomes shorter near noon due to the higher position of the Sun.
Class 7 Science Practice Questions For School Exam
A school exam can test definitions, observations, diagrams, and reason-based answers together. These Class 7 Science Practice Questions For School Exam also support revision for Class 7 Science Exam Questions from the 2026 NCERT pattern.
56. Why should a circuit diagram use standard symbols?
A circuit diagram should use standard symbols because they make the diagram clear and uniform.
Symbols help students and teachers understand the circuit quickly. They also avoid confusion caused by drawing objects differently.
Answer: Standard symbols make circuit diagrams clear and easy to read.
57. Why should a speed answer include units?
A speed answer should include units because speed depends on distance and time.
For example, 40 alone is incomplete. The correct answer should be 40 km/h if distance is in kilometres and time is in hours.
Answer: Speed must include units such as m/s or km/h.
58. Why should photosynthesis answers mention sunlight and chlorophyll?
Photosynthesis answers should mention sunlight and chlorophyll because both are essential for food-making.
Sunlight provides energy. Chlorophyll helps leaves trap that energy. Carbon dioxide and water form glucose in green plants.
Answer: Sunlight and chlorophyll are essential for photosynthesis.
59. Why should a reflection answer mention a smooth surface?
A reflection answer should mention a smooth surface because it gives a clear image.
Mirrors reflect light regularly because their surface is smooth. Rough surfaces scatter light and do not form clear images.
Answer: Smooth surfaces give clearer reflection.
60. Why should Moon phase answers mention reflected sunlight?
Moon phase answers should mention reflected sunlight because the Moon has no light of its own.
The Moon reflects sunlight. We see different portions of its sunlit half as it moves around Earth.
Answer: Moon phases depend on reflected sunlight and the Moon’s position.
Important Links Class 7 Science