Quiz Category · Science
Science
Biology, chemistry, physics, and the natural world.
From cells and circuits to stars and species — a steady stream of questions across the major scientific disciplines.
Science questions here cover the main school subjects: biology (cells, organs, classification), chemistry (elements, symbols, bonds), physics (forces, energy, light) and earth and space science (the planets, rocks, the atmosphere). Easy rounds stay with facts from early secondary school: what plants take in from the air, what the centre of an atom is called, which planet is closest to the Sun. Medium rounds expect a working knowledge of the periodic table, basic genetics and common formulae. Hard rounds go into topics such as quantum physics, isotopes and the modern definitions of physical constants. The questions are about general science literacy rather than exam preparation — they aren't written to the NEET or JEE syllabus, which goes much deeper. Useful for school students, for adults refreshing what they learned, and for anyone who likes a science round at a quiz night.
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10 questions per round23 science questions with answers
Across easy, medium and hard · reveal each answer to check yourself-
01 What gas do plants absorb from the atmosphere? easy
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The correct answer is C. Carbon Dioxide.
Plants draw carbon dioxide in through pores called stomata and combine it with water and sunlight to build sugars during photosynthesis. Oxygen is the by-product they release, which is why oxygen is the tempting wrong answer here.
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02 How many bones are in the adult human body? easy
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The correct answer is A. 206.
Adults have 206. Babies start with around 270, but many fuse during growth — most obviously in the skull and the sacrum — which is why the adult count is lower than the newborn one.
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03 What is the center of an atom called? easy
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The correct answer is C. Nucleus.
The nucleus holds the protons and neutrons, and therefore almost all of the atom's mass, inside a tiny fraction of its volume. Electrons occupy the vastly larger space around it.
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04 What is the chemical formula for water? easy
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The correct answer is B. H₂O.
Two hydrogen atoms bonded to one oxygen atom. The subscript applies only to the hydrogen, which is what separates water from hydrogen peroxide, H₂O₂.
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05 What planet is closest to the Sun? easy
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The correct answer is C. Mercury.
Mercury orbits at roughly 58 million km. It is not the hottest planet, though — Venus is, because its thick carbon dioxide atmosphere traps heat that near-airless Mercury cannot hold.
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06 What is the boiling point of water? easy
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The correct answer is B. 100°C.
100°C at standard atmospheric pressure, at sea level. Reduce the pressure and the boiling point falls, which is why water boils below 100°C at altitude and food takes longer to cook there.
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07 What force keeps us on the ground? easy
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The correct answer is C. Gravity.
Gravity is the mutual attraction between masses. Earth's mass pulls you toward its centre, and you pull back with equal force — Earth is simply so massive that its response is immeasurable.
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08 What is the largest organ in the human body? easy
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The correct answer is D. Skin.
Skin covers roughly 1.5–2 m² in an adult and makes up about 15% of body weight, which makes it the largest organ by both surface area and mass.
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09 What is the atomic number of carbon? medium
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The correct answer is B. 6.
Atomic number counts protons, so every carbon atom has exactly six. Change that count and you change the element entirely; change the neutron count instead and you get an isotope such as carbon-14.
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10 What type of bond involves sharing electrons? medium
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The correct answer is C. Covalent.
Covalent bonds share electron pairs between atoms. Ionic bonds transfer electrons outright and metallic bonds pool them across a lattice — the sharing is precisely what makes a bond covalent.
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11 What is the study of fungi called? medium
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The correct answer is B. Mycology.
Mycology. It sits apart from botany because fungi are not plants: they have no chlorophyll, cannot photosynthesise, and are genetically closer to animals than to plants.
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12 What is the pH of pure water? medium
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The correct answer is B. 7.
Pure water is neutral at pH 7 (at 25°C), with equal concentrations of H⁺ and OH⁻ ions. The scale is logarithmic, so pH 5 is a hundred times more acidic than pH 7, not slightly.
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13 What particle has no electric charge? medium
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The correct answer is C. Neutron.
Neutrons are electrically neutral, protons positive and electrons negative. That neutrality lets neutrons pass through matter without being deflected by charge, which is what makes them useful for probing materials.
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14 What is Newton's first law of motion? medium
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The correct answer is C. An object in motion stays in motion.
An object in motion stays in motion, and an object at rest stays at rest, unless acted on by an external force. It is also known as the law of inertia.
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15 What is the most abundant gas in Earth's atmosphere? medium
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The correct answer is C. Nitrogen.
Nitrogen accounts for about 78% of the atmosphere by volume, oxygen roughly 21%. Nitrogen's strong triple bond makes it largely unreactive, which is a large part of why it accumulated.
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16 What is the Heisenberg Uncertainty Principle? hard
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The correct answer is B. Position and momentum cannot be precisely measured simultaneously.
A particle's position and momentum cannot both be known with arbitrary precision — fix one more tightly and the other necessarily becomes less defined. This is a property of quantum systems themselves, not a shortcoming of measuring instruments.
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17 What is the name of the effect where light is bent by gravity? hard
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The correct answer is B. Gravitational Lensing.
Gravitational lensing. Mass curves spacetime, so light following the straightest path available to it bends around massive objects. General relativity predicted the effect; the 1919 solar eclipse confirmed it.
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18 What is the molecular formula of glucose? hard
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The correct answer is A. C₆H₁₂O₆.
Six carbon atoms, twelve hydrogen, six oxygen. Fructose and galactose share that exact formula but arrange the atoms differently, making them structural isomers of glucose.
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19 What is the Avogadro's number? hard
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The correct answer is A. 6.022 × 10²³.
6.022 × 10²³ is the number of particles in one mole. Since the 2019 SI redefinition it is a fixed, exactly defined constant rather than an experimentally measured quantity.
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20 What is the strongest known natural material? hard
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The correct answer is B. Graphene.
Graphene — a single layer of carbon atoms in a hexagonal lattice, with a measured tensile strength near 130 gigapascals, roughly 200 times stronger than steel by weight.
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21 What is the process of converting nitrogen gas into ammonia called? hard
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The correct answer is A. Nitrogen fixation.
Nitrogen fixation. Bacteria in legume root nodules do it biologically; the industrial Haber-Bosch process does it at scale and underpins most modern fertiliser production.
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22 What is the speed of light in a vacuum? hard
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The correct answer is A. 299,792,458 m/s.
Exactly 299,792,458 metres per second — exact because the metre is now defined in terms of it rather than measured against it. No information-carrying signal travels faster.
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23 What is the quantum of electromagnetic radiation called? hard
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The correct answer is C. Photon.
The photon: the quantum of the electromagnetic field, massless and always travelling at c. Its energy follows E = hf, so it is set entirely by frequency.
The full science pool runs to 331 questions — 107–115 questions per difficulty across easy, medium and hard. Each round you play is shuffled fresh, so the same ten never come up twice in a row. Pick a difficulty above to start a timed round, or scroll on for related categories.
Frequently asked questions
About the science quiz- What topics are covered in the science quiz?
- Biology, chemistry, physics, astronomy and earth science, at the level of general science literacy rather than specialist content.
- Is it suitable for school students?
- Yes. Easy and medium rounds map onto secondary-school science. Hard rounds include topics most people only meet in later study.
- Will it help with NEET or JEE?
- Only as light revision. Those exams test far more depth and problem-solving than a trivia-style quiz, so use subject-specific practice papers for them.
- Are medical questions included?
- Only basic anatomy and physiology, such as which organ produces insulin. There's no clinical content.