50 Science Trivia Questions and Answers, From the Human Body to Deep Space

Science has a reputation as the round that kills a friendly quiz, and it is undeserved. The bad science questions are the ones that need a degree. The good ones are the ones where the true answer is more interesting than the answer everyone assumes, and where the whole table goes quiet for a second before someone says wait, really?

Here are 50 science trivia questions and answers, from the human body to deep space, sorted easy to hard. A couple of the numbers below have been revised in the past few years, and the outdated versions are still circulating everywhere.

Warm-up (everyone scores here)

1. Which gas do plants take in to make their food?
Answer: Carbon dioxide.

2. What is the chemical symbol for iron?
Answer: Fe, from the Latin ferrum.

3. What is the center of an atom called?
Answer: The nucleus.

4. How many chambers does the human heart have?
Answer: Four.

5. What is the closest star to Earth?
Answer: The Sun. People overthink this one constantly.

6. At what temperature does water boil at sea level?
Answer: 100 degrees Celsius, or 212 Fahrenheit.

7. What is the study of fossils called?
Answer: Paleontology.

8. What is the largest organ in the human body?
Answer: The skin.

9. What do you call an animal that eats only plants?
Answer: A herbivore.

10. Which part of the cell produces most of its energy?
Answer: The mitochondria.

11. Which blood cells carry oxygen around the body?
Answer: Red blood cells.

12. What is the most abundant gas in Earth's atmosphere?
Answer: Nitrogen, at about 78 percent. Oxygen is only around 21.

The human body (closer to home, harder than it looks)

13. How many chromosomes does a human have?
Answer: 46, arranged in 23 pairs.

14. Which organ produces bile?
Answer: The liver. The gallbladder only stores it, which is why you can live fine without one.

15. What is the smallest bone in the human body?
Answer: The stapes, in the middle ear. It is about three millimetres long.

16. What is the hardest substance the human body produces?
Answer: Tooth enamel.

17. How many bones is a baby born with?
Answer: Around 300. Many of them fuse together as you grow, which is how you end up with 206 as an adult.

18. Which is longer, the small intestine or the large intestine?
Answer: The small intestine, at roughly six metres against about a metre and a half. Small refers to its width, not its length.

19. Which part of the brain handles balance and coordination?
Answer: The cerebellum.

20. How many basic tastes are officially recognized?
Answer: Five. Sweet, salty, sour, bitter, and umami. Umami was only widely accepted in the West in the last few decades, so older lists say four.

21. Which human organ can regenerate itself?
Answer: The liver. It can regrow to full size from a fraction of the original.

22. What is the most common blood type worldwide?
Answer: O positive.

Chemistry and physics (the round people fear)

23. How many elements are on the periodic table?
Answer: 118 confirmed. The newest is oganesson, element 118, named in 2016. Teams in Japan, the United States and Russia are all racing to make element 119, which would open an eighth row for the first time in decades.

24. What is the most abundant element in the universe?
Answer: Hydrogen, making up around three quarters of ordinary matter.

25. What is absolute zero?
Answer: Zero kelvin, which is minus 273.15 degrees Celsius. Nothing gets colder.

26. What does DNA stand for?
Answer: Deoxyribonucleic acid.

27. What is the speed of light in a vacuum?
Answer: 299,792,458 metres per second, or about 186,282 miles per second.

28. Which element has the symbol K?
Answer: Potassium, from the Latin kalium.

29. What is the pH of pure water?
Answer: 7, right in the middle of the scale.

30. Which subatomic particle carries no electric charge?
Answer: The neutron.

31. What does Newton's third law of motion say?
Answer: Every action has an equal and opposite reaction.

32. Which metal is liquid at room temperature?
Answer: Mercury. Gallium deserves partial credit: it is solid on the shelf but melts in your hand at about 30 degrees Celsius.

33. What does a half-life measure?
Answer: How long it takes for half of a radioactive sample to decay.

Space (the round worth losing sleep over)

34. Which planet has the shortest day?
Answer: Jupiter, which spins once in under 10 hours despite being the largest planet in the solar system.

35. Why is Pluto no longer classified as a planet?
Answer: Because it has not cleared its orbital neighbourhood, the third condition in the definition the International Astronomical Union adopted in 2006. It is a dwarf planet now.

36. Which large galaxy is closest to the Milky Way?
Answer: Andromeda, about 2.5 million light years away and heading toward us. Several dwarf galaxies are much closer, which is why the word large matters in the question.

37. How long does sunlight take to reach Earth?
Answer: About 8 minutes and 20 seconds.

38. What is Jupiter's Great Red Spot?
Answer: A storm wider than Earth that has been running for centuries. It has been shrinking noticeably in recent decades.

39. What does a light year measure?
Answer: Distance, not time. It is roughly 9.46 trillion kilometres.

40. Which planet rotates on its side?
Answer: Uranus, tilted about 98 degrees, so it effectively rolls around its orbit.

41. What is the boundary around a black hole called?
Answer: The event horizon. Cross it and nothing gets back out, light included.

42. Which planet is on average the closest to Earth?
Answer: Mercury, and almost every quiz sheet in the world says Venus. Venus does come nearer at its closest approach, but it also spends long stretches on the far side of the Sun. Averaged across time, Mercury is nearest to Earth. It is also the nearest planet on average to every other planet in the solar system, a result published in Physics Today in 2019.

43. What was the first artificial satellite?
Answer: Sputnik 1, launched by the Soviet Union in October 1957.

Hard round (the room goes quiet)

44. Which animal has survived direct exposure to the vacuum of space?
Answer: The tardigrade, also called the water bear. Some survived an orbital experiment in 2007 and went on to reproduce.

45. Which scientist has won Nobel Prizes in two different sciences?
Answer: Marie Curie, physics in 1903 and chemistry in 1911. She remains the only person to have done it.

46. Does sound travel faster through air or water?
Answer: Water, by roughly four times. Through steel it is faster still, because sound moves better the more tightly packed the material is.

47. What is the coldest temperature ever recorded at ground level on Earth?
Answer: About minus 89.2 degrees Celsius at Vostok Station in Antarctica in 1983. Satellites have since found surface patches down near minus 98, which is why you sometimes see the colder figure quoted.

48. What is the only mammal capable of true powered flight?
Answer: Bats. Flying squirrels glide, which is not the same thing.

49. Which planet has the most moons?
Answer: Saturn, and the number keeps moving. It sat at 83 a few years ago, jumped past 270 in 2025 when a batch of small outer moons was confirmed, and has kept climbing since. Jupiter, in second place, cracked 100 for the first time in 2026. Any specific number a quiz gives you is a snapshot.

50. Roughly how many of the cells in and on your body are not human?
Answer: About half. The old textbook line was that bacterial cells outnumber human ones ten to one, but a widely cited 2016 reassessment put the real ratio closer to one to one. The ten-to-one figure is still repeated constantly.

Keeping score

Out of 50: above 38 and you should be anchoring the science round for your team. 26 to 38 is a solid showing. Under 20 usually means the space section got you, and question 42 gets almost everybody.

Want more rounds? We have full sets for geography, history, movies, music, and sports, plus a general set that runs easy to brutal. If you enjoyed the corrections above, these are the facts almost everyone gets wrong, and if you are curious what all this quizzing does to you, we looked at whether trivia is actually good for your brain.

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