Science GK questions

GK by subject Updated 11 Oct 2026

These science gk questions cover physics, chemistry, biology and everyday science, with four options, the correct answer and a short explanation for every question. They suit school students, quiz contestants and anyone preparing for SSC, railway, bank or state exams where general science carries steady marks.

Each section starts with simple ideas and moves to the facts that exams ask again and again, such as SI units, chemical names, vitamins and the human body. Try every question before you check the answer, then read the explanation to learn the reason behind it.

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Physics GK questions

Q1. What is the SI unit of electrical resistance?
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Answer: A. Ohm
Resistance is measured in ohms, named after the German physicist Georg Simon Ohm.
Q2. Which instrument is used to measure atmospheric pressure?
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Answer: B. Barometer
A barometer measures air pressure; a hygrometer measures humidity and an anemometer measures wind speed.
Q3. What is the approximate speed of light in a vacuum?
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Answer: C. 3 x 10^8 m/s
Light travels about 300,000 km every second in a vacuum, which is 3 x 10^8 metres per second.
Q4. Which colour of visible light has the longest wavelength?
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Answer: D. Red
In the visible spectrum red light has the longest wavelength and violet light has the shortest.
Q5. Sound cannot travel through which of these?
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Answer: B. Vacuum
Sound is a mechanical wave and needs a medium of particles, so it cannot pass through empty space.
Q6. Which type of lens is used to correct short-sightedness (myopia)?
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Answer: A. Concave lens
A concave lens spreads light rays slightly so the image forms on the retina instead of in front of it.
Q7. What is the SI unit of power?
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Answer: C. Watt
Power is the rate of doing work; one watt equals one joule of work done per second.
Q8. Who gave the three laws of motion?
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Answer: D. Isaac Newton
Isaac Newton published the three laws of motion in his book Principia in 1687.
Q9. The twinkling of stars is caused by which phenomenon?
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Answer: A. Atmospheric refraction
Starlight bends again and again as it passes through layers of air of changing density, so the star appears to flicker.
Q10. One horsepower is roughly equal to how many watts?
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Answer: D. 746
One mechanical horsepower is about 746 watts, a unit first used by James Watt to compare engines with horses.
Q11. Which device converts mechanical energy into electrical energy?
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Answer: C. Electric generator
A generator works on electromagnetic induction; a motor does the opposite and turns electrical energy into motion.
Q12. Absolute zero, the lowest possible temperature, is equal to which value on the Celsius scale?
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Answer: B. -273.15 °C
Absolute zero is 0 kelvin, which equals -273.15 °C.
Q13. Sound waves with a frequency above 20,000 Hz are called what?
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Answer: C. Ultrasonic waves
Humans hear roughly 20 Hz to 20,000 Hz; sound above this range is ultrasound, used in medical scans and by bats.
Q14. What is the approximate value of acceleration due to gravity at the Earth's surface?
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Answer: D. 9.8 m/s²
Near the Earth's surface a falling object speeds up by about 9.8 metres per second every second; on the Moon it is about 1.6 m/s².

Chemistry GK questions

Q15. What is the chemical symbol of sodium?
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Answer: A. Na
The symbol Na comes from natrium, the Latin name for sodium.
Q16. What is the pH of pure water at 25 °C?
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Answer: B. 7
Pure water is neutral; a pH below 7 is acidic and above 7 is basic.
Q17. Which gas makes up the largest share of the Earth's atmosphere?
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Answer: B. Nitrogen
Nitrogen forms about 78 percent of dry air, while oxygen forms about 21 percent.
Q18. Diamond and graphite are both forms of which element?
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Answer: D. Carbon
Diamond and graphite are allotropes of carbon; their atoms are arranged differently, which gives them very different properties.
Q19. What is the chemical name of common salt?
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Answer: A. Sodium chloride
Common salt is sodium chloride, with the formula NaCl.
Q20. What is the chemical name of baking soda?
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Answer: C. Sodium hydrogen carbonate
Baking soda is sodium hydrogen carbonate (NaHCO3); on heating it releases carbon dioxide, which makes dough rise.
Q21. Which metal is a liquid at room temperature?
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Answer: D. Mercury
Mercury melts at about -39 °C, so it stays liquid at normal room temperature.
Q22. What is the atomic number of carbon?
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Answer: B. 6
A carbon atom has 6 protons; 12 is the mass number of the most common carbon isotope.
Q23. Which noble gas is commonly used to fill party balloons because it is lighter than air?
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Answer: C. Helium
Helium is much lighter than air and does not burn, so it is safe for balloons and airships.
Q24. Along with oxygen, what else does iron need in order to rust?
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Answer: A. Water
Rusting is the slow reaction of iron with oxygen in the presence of water, forming hydrated iron oxide.
Q25. What is the chemical formula of methane?
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Answer: B. CH4
Methane has one carbon atom bonded to four hydrogen atoms and is the main component of natural gas.
Q26. Vinegar contains which acid?
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Answer: A. Acetic acid
Vinegar is a dilute solution of acetic acid; citric acid is found in lemons and lactic acid in curd.
Q27. Which is the lightest element?
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Answer: C. Hydrogen
Hydrogen has atomic number 1 and is the lightest and most abundant element in the universe.
Q28. Which element has the chemical symbol K?
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Answer: D. Potassium
K comes from kalium, the Latin name for potassium; krypton is Kr and calcium is Ca.

Biology GK questions

Q29. Which cell organelle releases energy from food and is often called the powerhouse of the cell?
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Answer: B. Mitochondria
Mitochondria release energy from food through cellular respiration and store it as ATP.
Q30. Which part of the human eye controls the amount of light that enters it?
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Answer: D. Iris
The coloured iris changes the size of the pupil, letting in less light in bright conditions and more in dim light.
Q31. Which vitamin is made in the human skin when it is exposed to sunlight?
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Answer: C. Vitamin D
Sunlight helps the skin make vitamin D, which the body needs to absorb calcium for strong bones.
Q32. Which blood vessels carry blood away from the heart to the rest of the body?
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Answer: A. Arteries
Arteries carry blood away from the heart under high pressure, while veins bring blood back to the heart.
Q33. Which pigment gives plants their green colour?
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Answer: B. Chlorophyll
Chlorophyll absorbs sunlight for photosynthesis and reflects green light.
Q34. A person of which blood group can receive red blood cells from donors of every ABO and Rh group?
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Answer: C. AB positive
AB positive blood has A, B and Rh antigens and no anti-A or anti-B antibodies, so it is called the universal recipient.
Q35. Scurvy is caused by the deficiency of which vitamin?
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Answer: D. Vitamin C
Lack of vitamin C causes scurvy, with bleeding gums; lack of vitamin D causes rickets.
Q36. The stapes, the smallest bone in the human body, is found in which part of the body?
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Answer: A. Middle ear
The stapes is one of three tiny bones of the middle ear that pass sound vibrations from the eardrum to the inner ear.
Q37. Which organ produces the hormone insulin?
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Answer: D. Pancreas
Insulin is made by the islets of Langerhans in the pancreas and controls the level of sugar in the blood.
Q38. Which gas do green plants release during photosynthesis?
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Answer: A. Oxygen
Plants take in carbon dioxide and water and, using sunlight, make glucose and release oxygen.
Q39. Malaria is spread by the bite of which insect?
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Answer: C. Female Anopheles mosquito
The female Anopheles mosquito carries the Plasmodium parasite; Aedes mosquitoes spread dengue.
Q40. Which blood cells help the body fight infection?
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Answer: B. White blood cells
White blood cells attack germs; red blood cells carry oxygen and platelets help blood to clot.
Q41. How many bones are there in the body of an adult human?
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Answer: A. 206
A newborn has about 300 bones, but many fuse during growth, leaving 206 in an adult.
Q42. Who is known as the father of genetics?
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Answer: C. Gregor Mendel
Gregor Mendel worked out the basic laws of inheritance through his experiments on pea plants.

Everyday science questions with answers

Q43. Why does ice float on water?
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Answer: B. Ice is less dense than water
Water expands when it freezes, so ice has a lower density than liquid water and floats on it.
Q44. Which gas is dissolved in soda water to make it fizzy?
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Answer: D. Carbon dioxide
Carbon dioxide is dissolved under pressure; when the bottle is opened the gas escapes as bubbles.
Q45. LPG used in kitchens is mainly a mixture of which gases?
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Answer: D. Butane and propane
Liquefied petroleum gas is mostly butane and propane; a smelly compound is added so leaks can be noticed.
Q46. Fluoride is added to toothpaste mainly to do what?
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Answer: A. Prevent tooth decay
Fluoride makes tooth enamel stronger and more resistant to acids made by bacteria.
Q47. Iodised salt helps to prevent which disease?
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Answer: C. Goitre
Iodine is needed by the thyroid gland; its shortage can cause swelling of the thyroid called goitre.
Q48. Why does a pressure cooker cook food faster?
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Answer: B. It raises the boiling point of water
The trapped steam increases the pressure inside, so water boils above 100 °C and food cooks faster.
Q49. Bleaching powder is commonly used to do what?
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Answer: D. Disinfect drinking water
Bleaching powder releases chlorine, which kills germs in water.
Q50. A household fuse wire melts and breaks the circuit because of which effect of electricity?
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Answer: A. Heating effect
When too much current flows, the fuse wire heats up and melts, breaking the circuit.
Q51. Which bacteria help to turn milk into curd?
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Answer: B. Lactobacillus
Lactobacillus bacteria change milk sugar (lactose) into lactic acid, which sets the milk into curd.
Q52. Dry ice is the solid form of which substance?
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Answer: C. Carbon dioxide
Solid carbon dioxide is called dry ice because it turns straight into gas without melting into a liquid.
Q53. Why do we see lightning before we hear thunder?
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Answer: D. Light travels faster than sound
Lightning and thunder happen together, but light reaches us almost instantly while sound covers only about 343 metres per second in air.
Q54. What is the frequency of the AC mains supply in Indian homes?
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Answer: C. 50 Hz
India supplies household AC at about 230 volts and 50 hertz.
Q55. Which gas is commonly called laughing gas?
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Answer: B. Nitrous oxide
Nitrous oxide (N2O) is used as a mild anaesthetic and can cause a feeling of laughter.

How to prepare

Use these science gk questions as a quick revision test. Attempt one section at a time without looking at the options first, then compare your answer. When you get one wrong, note the fact from the explanation in a small notebook under the heading physics, chemistry or biology. Over a few weeks this becomes your own short revision sheet for the night before an exam.

Most general science questions in competitive exams come from NCERT books of classes 6 to 10. Read those chapters along with this quiz: units and instruments in physics, symbols, formulas and everyday chemicals in chemistry, and vitamins, diseases, cells and organs in biology. Linking each fact to something you see at home, such as curd, soda or a pressure cooker, makes it much easier to remember.

Study tips

Learn SI units and the instruments that measure each quantity as one list, because exams often pair them.
Make a table of vitamins with their sources and deficiency diseases and revise it every week.
Read the NCERT science books of classes 6 to 10, since most general science questions are based on them.

Questions people ask

What are the most important science gk questions for competitive exams?

Questions on SI units, measuring instruments, chemical names of common substances, vitamins and deficiency diseases, human body organs and everyday science are asked most often. These topics come straight from NCERT books and appear in SSC, railway and state exams every year.

How should I prepare physics, chemistry and biology questions for general science?

Start with NCERT books of classes 6 to 10 and make short notes for each subject. Then practise multiple choice questions like the ones on this page and revise the facts you get wrong.

Are these science quiz questions suitable for school students?

Yes. The questions use simple language and cover topics taught from class 6 onwards, so school students can use them for quizzes, olympiad practice and class tests.

Which science topics are easiest to score in exams?

Everyday science, vitamins and diseases, units and instruments, and common chemical names are the easiest to score because the facts are fixed and the questions are direct. A little regular revision is enough to answer them correctly.

Every question on this page is written and fact-checked by the GK Quizzes team. Spotted a mistake? Tell us and we will fix it. How we make our questions.