iOS Important Questions for 2025-26 Exam: The International Olympiad of Science (iOS) is a prestigious examination conducted by the SilverZone Foundation that aims to assess the scientific knowledge and aptitude of students from Class 1 to Class 12. As the 2025-26 session approaches, students and parents are increasingly seeking structured preparation material. One of the most effective strategies for preparation is focusing on the most important questions derived from the syllabus and previous exam patterns.
This article provides class-wise important questions for the iOS 2025-26 exam, helping students prepare efficiently and score high. Whether you’re in Class 3 or Class 12, this guide offers valuable insights into the types of questions you can expect in the upcoming exam.
Why Focus on iOS Important Questions?
Important questions are selected based on:
- Analysis of past year iOS papers
- Frequently asked concepts
- Core topics from the syllabus
- Recommendations by subject experts
Focusing on important questions improves accuracy, saves time during revision, and boosts confidence before the exam.
Class-Wise iOS 2025-26 Important Questions
Below is a breakdown of some important questions by class and subject. These are meant for reference and practice and may not be the exact questions in the exam, but they represent commonly tested concepts.
Class 1 iOS Important Questions
-
Which of the following is a living thing?
-
(A) Chair
-
(B) Rabbit
-
(C) Car
-
(D) Table
-
-
Which part of the plant is responsible for making food?
-
(A) Root
-
(B) Stem
-
(C) Leaf
-
(D) Flower
-
-
Identify the animal that can live both on land and in water.
-
(A) Dog
-
(B) Frog
-
(C) Cat
-
(D) Cow
-
-
Which of the following is used to tell time?
-
(A) Thermometer
-
(B) Clock
-
(C) Scale
-
(D) Compass
-
-
What do we wear to protect ourselves from rain?
-
(A) Sweater
-
(B) Raincoat
-
(C) Cap
-
(D) Gloves
-
-
Which sense organ helps us to hear sounds?
-
(A) Eyes
-
(B) Nose
-
(C) Ears
-
(D) Tongue
-
-
Which of the following is a healthy food item?
-
(A) Chips
-
(B) Burger
-
(C) Fruits
-
(D) Candy
-
-
Which of these is a source of light?
-
(A) Moon
-
(B) Sun
-
(C) Mirror
-
(D) Window
-
-
Which animal is known as the ‘King of the Jungle’?
-
(A) Elephant
-
(B) Tiger
-
(C) Lion
-
(D) Bear
-
-
Which of the following is used to clean teeth?
-
(A) Comb
-
(B) Toothbrush
-
(C) Spoon
-
(D) Knife
-
Class 2 iOS Important Questions
-
Which of the following is a herbivore?
-
(A) Lion
-
(B) Cow
-
(C) Tiger
-
(D) Leopard
-
-
What do we use to measure temperature?
-
(A) Thermometer
-
(B) Barometer
-
(C) Speedometer
-
(D) Hygrometer
-
-
Which gas do plants release during photosynthesis?
-
(A) Oxygen
-
(B) Carbon dioxide
-
(C) Nitrogen
-
(D) Hydrogen
-
-
Which part of the plant absorbs water from the soil?
-
(A) Leaf
-
(B) Stem
-
(C) Root
-
(D) Flower
-
-
Which of the following is a non-living thing?
-
(A) Cat
-
(B) Tree
-
(C) Rock
-
(D) Fish
-
-
Which of these animals lays eggs?
-
(A) Cow
-
(B) Dog
-
(C) Hen
-
(D) Cat
-
-
Which of the following is a natural source of water?
-
(A) Tap
-
(B) River
-
(C) Bottle
-
(D) Tank
-
-
What is the main source of energy for Earth?
-
(A) Moon
-
(B) Stars
-
(C) Sun
-
(D) Fire
-
-
Which of these is a sense organ?
-
(A) Hand
-
(B) Leg
-
(C) Ear
-
(D) Hair
-
-
Which of the following is used to cut paper?
-
(A) Spoon
-
(B) Scissors
-
(C) Fork
-
(D) Knife
-
Class 3 iOS Important Questions
-
Which of the following is a carnivorous animal?
-
(A) Cow
-
(B) Goat
-
(C) Lion
-
(D) Deer
-
-
What is the process by which plants make their food?
-
(A) Respiration
-
(B) Digestion
-
(C) Photosynthesis
-
(D) Transpiration
-
-
Which part of the human body helps in pumping blood?
-
(A) Lungs
-
(B) Brain
-
(C) Heart
-
(D) Liver
-
-
Which of these is a renewable source of energy?
-
(A) Coal
-
(B) Oil
-
(C) Wind
-
(D) Natural Gas
-
-
Which of the following is a solid state of water?
-
(A) Steam
-
(B) Ice
-
(C) Water vapor
-
(D) None of these
-
-
Which planet is known as the ‘Red Planet’?
-
(A) Earth
-
(B) Mars
-
(C) Jupiter
-
(D) Venus
-
-
Which of these animals is a reptile?
-
(A) Frog
-
(B) Snake
-
(C) Whale
-
(D) Penguin
-
-
What do we call animals that eat both plants and animals?
-
(A) Herbivores
-
(B) Carnivores
-
(C) Omnivores
-
(D) Insectivores
-
-
Which of the following helps in digestion of food?
-
(A) Heart
-
(B) Lungs
-
(C) Stomach
-
(D) Brain
-
-
Which of these is a man-made source of light?
-
(A) Sun
-
(B) Moon
-
(C) Lamp
-
(D) Star
-
Class 4 iOS Important Questions
-
Which of the following is a conductor of electricity?
-
(A) Plastic
-
(B) Wood
-
(C) Copper
-
(D) Rubber
-
-
What is the boiling point of water?
-
(A) 0°C
-
(B) 50°C
-
(C) 100°C
-
(D) 212°C
-
-
Which gas is essential for human respiration?
-
(A) Nitrogen
-
(B) Oxygen
-
(C) Carbon dioxide
-
(D) Hydrogen
-
-
Which organ is responsible for filtering blood in the human body?
-
(A) Heart
-
(B) Liver
-
(C) Kidney
-
(D) Lungs
-
-
Which of the following is a non-renewable source of energy?
-
(A) Solar
-
(B) Wind
-
(C) Coal
-
(D) Hydro
-
-
What is the process of water changing into vapor called?
-
(A) Condensation
-
(B) Evaporation
-
(C) Precipitation
-
(D) Sublimation
-
-
Which part of the plant conducts water from roots to leaves?
-
(A) Stem
-
(B) Leaf
-
(C) Flower
-
(D) Fruit
-
-
Which of these is a vertebrate?
-
(A) Earthworm
-
(B) Snail
-
(C) Fish
-
(D) Octopus
-
-
Which of the following is a natural satellite of Earth?
-
(A) Mars
-
(B) Sun
-
(C) Moon
-
(D) Venus
-
-
Which of these is a simple machine?
-
(A) Car
-
(B) Bicycle
-
(C) Lever
-
(D) Engine
-
Class 5 iOS Important Questions
-
Which of the following is a communicable disease?
-
(A) Diabetes
-
(B) Cancer
-
(C) Tuberculosis
-
(D) Hypertension
-
-
What is the main function of white blood cells?
-
(A) Carry oxygen
-
(B) Fight infections
-
(C) Clot blood
-
(D) Provide energy
-
-
Which of the following is a metamorphic rock?
-
(A) Granite
-
(B) Marble
-
(C) Sandstone
-
(D) Limestone
-
-
Which planet has the largest number of moons?
-
(A) Earth
-
(B) Mars
-
(C) Jupiter
-
(D) Saturn
-
-
Which of these is a chemical change?
-
(A) Melting ice
-
(B) Boiling water
-
(C) Burning paper
-
(D) Breaking glass
-
-
What is the function of the ozone layer?
-
Which of the following is a renewable resource?
-
(A) Petroleum
-
(B) Coal
-
(C) Natural gas
-
(D) Solar energy
-
-
What is the main source of energy for the water cycle?
-
(A) Wind
-
(B) Sun
-
(C) Moon
-
(D) Earth’s core
-
-
Which organelle is known as the ‘powerhouse of the cell’?
-
Which of the following is used to measure wind speed?
-
(A) Thermometer
-
(B) Barometer
-
(C) Anemometer
-
Class 6 iOS Important Questions
-
Which component of food is essential for body growth and repair?
-
(A) Carbohydrates
-
(B) Fats
-
(C) Proteins
-
(D) Vitamins
-
-
Which process separates solid particles from a liquid using a filter?
-
(A) Sedimentation
-
(B) Filtration
-
(C) Decantation
-
(D) Evaporation
-
-
What is the function of xylem in plants?
-
(A) Transport of food
-
(B) Transport of water
-
(C) Photosynthesis
-
(D) Reproduction
-
-
Which of the following is a non-contact force?
-
(A) Friction
-
(B) Muscular force
-
(C) Magnetic force
-
(D) Tension
-
-
Which of these is a good conductor of electricity?
-
(A) Plastic
-
(B) Wood
-
(C) Copper
-
(D) Rubber
-
-
What is the boiling point of water at sea level?
-
(A) 90°C
-
(B) 100°C
-
(C) 110°C
-
(D) 120°C
-
-
Which gas is essential for combustion?
-
(A) Nitrogen
-
(B) Oxygen
-
(C) Carbon dioxide
-
(D) Hydrogen
-
-
Which of the following is a reversible change?
-
(A) Burning of paper
-
(B) Melting of ice
-
(C) Rusting of iron
-
(D) Cooking of food
-
-
Which organelle is known as the ‘powerhouse of the cell’?
-
What is the primary source of energy for the Earth?
-
(A) Moon
-
(B) Stars
-
(C) Sun
-
(D) Earth’s core
-
Class 7 iOS Important Questions
-
Which of the following is a physical change?
-
(A) Burning of wood
-
(B) Rusting of iron
-
(C) Melting of ice
-
(D) Digestion of food
-
-
What is the SI unit of force?
-
(A) Newton
-
(B) Joule
-
(C) Pascal
-
(D) Watt
-
-
Which part of the plant is responsible for reproduction?
-
(A) Root
-
(B) Stem
-
(C) Leaf
-
(D) Flower
-
-
Which of the following is a non-metal?
-
(A) Iron
-
(B) Copper
-
(C) Sulfur
-
(D) Aluminum
-
-
What is the function of the respiratory system?
-
(A) Circulation of blood
-
(B) Digestion of food
-
(C) Exchange of gases
-
(D) Excretion of waste
-
-
Which of these is a renewable source of energy?
-
(A) Coal
-
(B) Oil
-
(C) Wind
-
(D) Natural gas
-
-
Which of the following is a homogeneous mixture?
-
Which organ in the human body is responsible for filtering blood?
-
(A) Heart
-
(B) Liver
-
(C) Kidney
-
(D) Lungs
-
-
What is the process by which plants lose water vapor through their leaves?
-
(A) Photosynthesis
-
(B) Respiration
-
(C) Transpiration
-
(D) Germination
-
-
Which of the following is a conductor of electricity?
-
(A) Glass
-
(B) Rubber
-
(C) Silver
-
(D) Plastic
-
Class 8 iOS Important Questions
-
Which of the following is a chemical change?
-
(A) Melting of ice
-
(B) Boiling of water
-
(C) Rusting of iron
-
(D) Breaking of glass
-
-
What is the function of red blood cells?
-
(A) Fight infections
-
(B) Clot blood
-
(C) Carry oxygen
-
(D) Produce hormones
-
-
Which of the following is a non-renewable source of energy?
-
(A) Solar energy
-
(B) Wind energy
-
(C) Coal
-
(D) Hydroelectric power
-
-
Which of these is a noble gas?
-
(A) Oxygen
-
(B) Nitrogen
-
(C) Helium
-
(D) Hydrogen
-
-
What is the chemical formula of water?
-
(A) CO₂
-
(B) H₂O
-
(C) O₂
-
(D) HCl
-
-
Which part of the cell contains genetic material?
-
(A) Cytoplasm
-
(B) Nucleus
-
(C) Mitochondria
-
(D) Ribosome
-
-
Which of the following is a greenhouse gas?
-
(A) Oxygen
-
(B) Nitrogen
-
(C) Carbon dioxide
-
(D) Hydrogen
-
-
What is the process of conversion of water vapor into liquid called?
-
(A) Evaporation
-
(B) Condensation
-
(C) Sublimation
-
(D) Precipitation
-
-
Which of the following is an example of a unicellular organism?
-
(A) Amoeba
-
(B) Hydra
-
(C) Earthworm
-
(D) Butterfly
-
-
Which of the following is used to measure atmospheric pressure?
-
(A) Thermometer
-
(B) Barometer
-
(C) Hygrometer
-
(D) Anemometer
-
Class 9 iOS Important Questions
-
Which of the following is a scalar quantity?
-
(A) Velocity
-
(B) Force
-
(C) Speed
-
(D) Acceleration
-
-
What is the acceleration due to gravity on Earth?
-
(A) 9.8 m/s²
-
(B) 9.8 km/s²
-
(C) 9.8 cm/s²
-
(D) 9.8 mm/s²
-
-
Which of the following is a chemical reaction?
-
What is the pH value of a neutral solution?
-
(A) 0
-
(B) 7
-
(C) 14
-
(D) 10
-
-
Which of the following is a covalent compound?
-
(A) NaCl
-
(B) KBr
-
(C) H₂O
-
(D) MgO
-
-
What is the unit of electric current?
-
(A) Volt
-
(B) Ohm
-
(C) Ampere
-
(D) Watt
-
-
Which of the following is a renewable source of energy?
-
(A) Petroleum
-
(B) Natural gas
-
(C) Wind energy
-
(D) Coal
-
-
Which of the following is an example of a chemical change?
-
(A) Freezing of water
-
(B) Boiling of water
-
(C) Rusting of iron
-
(D) Melting of ice
-
-
What is the main function of the human respiratory system?
-
(A) Circulation of blood
-
(B) Digestion of food
-
(C) Exchange of gases
-
(D) Excretion of waste
-
-
Which of the following is a non-metal?
-
(A) Sodium
-
(B) Iron
-
(C) Chlorine
-
(D) Copper
-
Class 10 iOS Important Questions
-
What is the chemical formula of calcium carbonate?
-
(A) CaCO₃
-
(B) CaCl₂
-
(C) CaSO₄
-
(D) CaO
-
-
Which of the following is a strong acid?
-
(A) HCl
-
(B) CH₃COOH
-
(C) H₂CO₃
-
(D) H₂O
-
-
What is the unit of electric power?
-
(A) Volt
-
(B) Ampere
-
(C) Watt
-
(D) Ohm
-
-
Which of the following is a greenhouse gas?
-
(A) Oxygen
-
(B) Nitrogen
-
(C) Carbon dioxide
-
(D) Hydrogen
-
-
What is the process of conversion of a solid directly into gas called?
-
(A) Evaporation
-
(B) Condensation
-
(C) Sublimation
-
(D) Melting
-
-
Which of the following is a covalent compound?
-
(A) NaCl
-
(B) KBr
-
(C) H₂O
-
(D) MgO
-
Class 11 iOS Important Questions
-
Which of the following is a vector quantity?
(A) Work
(B) Power
(C) Displacement
(D) Speed -
What is the dimensional formula of force?
(A) [MLT⁻²]
(B) [ML²T⁻¹]
(C) [ML⁻¹T⁻²]
(D) [M²LT⁻²] -
The escape velocity from the surface of Earth is approximately:
(A) 9.8 km/s
(B) 7.9 km/s
(C) 11.2 km/s
(D) 15.6 km/s -
What is the acceleration of an object moving in a uniform circular motion?
(A) Zero
(B) Constant
(C) Directed towards the center
(D) Away from the center -
If a spring is stretched to double its length, the potential energy becomes:
(A) Half
(B) Double
(C) Four times
(D) Same -
The shape of the p-orbital is:
(A) Spherical
(B) Dumbbell
(C) Circular
(D) Elliptical -
Which of the following is a Lewis acid?
(A) NH₃
(B) H₂O
(C) BF₃
(D) OH⁻ -
Which law states that the total pressure exerted by a mixture of gases is equal to the sum of partial pressures?
(A) Boyle’s Law
(B) Charles’ Law
(C) Dalton’s Law
(D) Avogadro’s Law -
Which plant hormone is responsible for cell elongation?
(A) Cytokinin
(B) Gibberellin
(C) Auxin
(D) Abscisic acid -
Which phase of the cell cycle is responsible for DNA replication?
(A) G1 Phase
(B) S Phase
(C) G2 Phase
(D) M Phase
Class 12 iOS Important Questions
-
Which of the following is true about electric field lines?
(A) They form closed loops
(B) They intersect each other
(C) They originate from negative charges
(D) They originate from positive and end at negative charges -
A transformer works on the principle of:
(A) Ohm’s law
(B) Electromagnetic induction
(C) Capacitance
(D) Resistance -
In photoelectric effect, the energy of emitted electrons depends on:
(A) Intensity of light
(B) Frequency of light
(C) Duration of exposure
(D) Area of the metal plate -
The unit of magnetic flux is:
(A) Tesla
(B) Weber
(C) Henry
(D) Farad -
What is the focal length of a concave mirror if the radius of curvature is 20 cm?
(A) 10 cm
(B) 20 cm
(C) 40 cm
(D) 5 cm -
Which of the following is used as a primary standard in acid-base titration?
(A) NaOH
(B) HCl
(C) Na₂CO₃
(D) NH₄OH -
Which compound exhibits resonance?
(A) C₂H₆
(B) CH₄
(C) C₆H₆
(D) C₂H₅OH -
Which of the following is the strongest oxidising agent?
(A) Cl₂
(B) F₂
(C) Br₂
(D) I₂ -
Which part of the nephron is responsible for ultrafiltration?
(A) Loop of Henle
(B) Bowman’s capsule
(C) Collecting duct
(D) Proximal convoluted tubule -
Which of the following diseases is caused due to autosomal recessive disorder?
(A) Hemophilia
(B) Down syndrome
(C) Sickle cell anemia
(D) Color blindness
Tips for Using iOS Important Questions Effectively
- Solve with a Timer: This simulates the exam environment.
- Understand the Concept: Don’t just memorize, understand the reasoning.
- Revise Regularly: Go over these questions weekly for better retention.
- Use NCERT Books: Most questions are based on NCERT fundamentals.
- Take Mock Tests: Include these questions in mock test practice.
Where to Find More iOS Practice Questions?
You can find additional practice material and sample questions on:
- The official SilverZone Olympiad website
- Aakash Institute practice modules
- NCERT textbooks and guides
- Olympiad-specific books and guides available online or in stores
Conclusion
The iOS 2025-26 Exam demands a deep understanding of scientific principles and a structured approach to preparation. By focusing on class-wise important questions, students can maximize their performance and approach the exam with greater confidence.
Use this guide to plan your revision effectively and don’t forget to complement these questions with full-length practice tests and solution-based learning. Let this article serve as your go-to resource for revising the most relevant and likely questions for iOS 2025-26.
iOS Important Questions for 2025-26 Exam FAQs
Q1. What type of questions are asked in the iOS 2025–26 Exam?
Ans: The iOS exam primarily includes Multiple Choice Questions (MCQs) that test both conceptual understanding and application skills in Science (Physics, Chemistry, Biology) based on the student’s current academic level (Class 1 to 12). The questions are designed to align with NCERT/CBSE/ICSE and other state boards.
Q2. Are iOS important questions the same as textbook questions?
Ans: Not exactly. While textbook concepts are essential, iOS important questions go beyond textbooks by testing critical thinking, real-world applications, and Olympiad-level logic. They are curated specifically to help students prepare for competitive assessments.
Q3. Where can I find class-wise iOS important questions for practice?
Ans: You can find class-wise iOS important questions through:
-
Official iOS preparatory books
-
Aakash iOS Olympiad resources
-
School Olympiad practice sheets
-
Online platforms providing sample papers and previous year questions tailored to IOS
Q4. Are iOS important questions available with solutions?
Ans: Yes, many sources provide iOS important questions along with detailed solutions. This helps students to understand the correct methodology and improve problem-solving skills. Practicing solved questions enhances confidence for the actual exam.
Q5. How should I use the iOS important questions for effective revision?
Ans: Follow this strategy:
-
Practice 5–10 questions daily from each section.
-
Attempt topic-wise MCQs after reading the chapter.
-
Solve mock tests and sample papers weekly.
-
Use solutions to learn explanations and eliminate guesswork.