What is science MCq 1. What is the boiling point of water at sea level? A) 90°C B) 100°C C) 110°C D) 120°C Answer: B 2. Which gas is essential for respiration? A) Carbon dioxide B) Oxygen C) Nitrogen D) Hydrogen Answer: B 3. The SI unit of force is: A) Kilogram B) Newton C) Joule D) Watt Answer: B 4. What part of the plant conducts photosynthesis? A) Root B) Stem C) Leaf D) Flower Answer: C 5. Which organ purifies blood in the human body? A) Liver B) Heart C) Kidney D) Lungs Answer: C 6. The hardest natural substance is: A) Gold B) Diamond C) Iron D) Platinum Answer: B 7. What is the chemical symbol for water? A) O2 B) H2 C) CO2 D) H2O Answer: D 8. What gas do plants absorb from the atmosphere? A) Oxygen B) Nitrogen C) Carbon dioxide D) Hydrogen Answer: C 9. The largest planet in the solar system is: A) Earth B) Jupiter C) Saturn D) Mars Answer: B 10. Which vitamin is produced in the skin by sunlight? A) A B) B C) C D) D Answer: D --- More MCQs (11–50) 11. What is the main gas found in the air we breathe? Answer: B) Nitrogen 12. Which part of the atom has no electric charge? Answer: C) Neutron 13. Which planet is known as the Red Planet? Answer: A) Mars 14. What is the center of an atom called? Answer: D) Nucleus 15. What is the pH value of pure water? Answer: C) 7 16. Which instrument is used to measure temperature? Answer: A) Thermometer 17. What do you call animals that eat only plants? Answer: B) Herbivores 18. The speed of light is approximately? Answer: D) 300,000 km/s 19. Which element is needed for hemoglobin in blood? Answer: C) Iron 20. What is the nearest star to Earth? Answer: A) Sun 21. The process of liquid changing to gas is called? Answer: C) Evaporation 22. Sound travels fastest through which medium? Answer: B) Solid 23. Which blood cells help fight infection? Answer: D) White blood cells 24. Which part of the brain controls balance? Answer: C) Cerebellum 25. What is the smallest unit of life? Answer: A) Cell 26. The most abundant element in the universe is? Answer: A) Hydrogen 27. Which organ controls the entire body? Answer: B) Brain 28. Acid rain is caused mainly by? Answer: C) Sulphur dioxide 29. Which vitamin helps with blood clotting? Answer: D) Vitamin K 30. A push or pull on an object is called? Answer: B) Force 31. Which of these is not a state of matter? Answer: D) Energy 32. The Earth rotates on its axis once every? Answer: A) 24 hours 33. What is the chemical formula of salt? Answer: C) NaCl 34. What organ pumps blood through the body? Answer: A) Heart 35. Which metal is liquid at room temperature? Answer: B) Mercury 36. What is used to measure electric current? Answer: D) Ammeter 37. Which natural disaster is measured by the Richter scale? Answer: A) Earthquake 38. Which planet has the most moons? Answer: B) Saturn 39. Which part of the eye controls the amount of light? Answer: C) Iris 40. What is the main function of red blood cells? Answer: D) Carry oxygen 41. Photosynthesis occurs in which cell organelle? Answer: A) Chloroplast 42. What substance do bees collect from flowers? Answer: B) Nectar 43. Which gas causes global warming? Answer: A) Carbon dioxide 44. What does DNA stand for? Answer: B) Deoxyribonucleic Acid 45. Which of these is a renewable energy source? Answer: D) Solar power 46. What is the freezing point of water? Answer: B) 0°C 47. The lungs are part of which system? Answer: A) Respiratory system 48. The study of living organisms is called? Answer: C) Biology 49. Which force pulls objects toward Earth? Answer: A) Gravity 50. Which organ is responsible for digestion of food? Answer: D) Stomach