Science trivia questions and answers
Ten questions we wrote ourselves, on facts that can be checked. Each answer names its source, and the numbers come from the same datasets as the rest of this site.
Updated on October 7, 2026
The questions
Answers are open, not hidden behind a click: a quiz you cannot verify is not worth much. Where an answer is a number from a dataset, our tests check that the two still agree.
1. How many chemical elements does the periodic table have today?
Answer: 118. The last four (nihonium, moscovium, tennessine and oganesson) had their names approved by IUPAC in 2016, completing period 7.
2. Which element has atomic number 79?
Answer: Gold, symbol Au, from the Latin aurum. Atomic number 79 means 79 protons in the nucleus.
3. What is the speed of light in vacuum?
Answer: Exactly 299,792,458 metres per second. It is not a measurement: since 1983 the metre is defined from this number, so the value has no uncertainty.
Source: NIST — CODATA Internationally Recommended Values of the Fundamental Physical Constants (2022)
4. Which metal is liquid at room temperature?
Answer: Mercury (Hg, element 80). Bromine is also liquid at 25 °C, but it is not a metal. Gallium and caesium melt just above room temperature.
5. What is the chemical formula of table salt?
Answer: NaCl, sodium chloride: one sodium ion for each chloride ion, with a molar mass of 58.44 g/mol.
6. How many protons does a carbon atom have?
Answer: 6. That is what makes it carbon; the number of neutrons varies between isotopes, from carbon-12 to carbon-14.
7. What is Avogadro's number?
Answer: 6.02214076 × 10²³ particles per mole, exact by definition since the 2019 revision of the SI, which stopped tying the mole to a kilogram of carbon-12.
Source: NIST — CODATA Internationally Recommended Values of the Fundamental Physical Constants (2022)
8. Which gas makes up most of Earth's atmosphere?
Answer: Nitrogen, about 78% of dry air by volume, against roughly 21% oxygen. Carbon dioxide is well under 1%.
Source: NASA — Planetary Fact Sheet (NSSDCA) e NASA Science: Solar System
9. What is the molar mass of water?
Answer: 18.015 g/mol: two hydrogens (1.008 each) plus one oxygen (15.999), using the IUPAC standard atomic weights.
10. Which element is named after Marie and Pierre Curie?
Answer: Curium, symbol Cm, element 96, first produced in 1944. Marie Curie also gave her name to polonium, after her native Poland.
Source: Cálculo próprio a partir dos dados citados nesta página
Why so few questions, and so many sources
Most trivia you find online has been copied between sites for years, and copying propagates errors: atomic weights from superseded tables, "facts" that were never true, answers that changed when a definition did. We would rather publish ten questions we can stand behind than two hundred we cannot.
If you spot a mistake, the source link next to each answer is the place to check it, and it should win against us.
Source: Cálculo próprio a partir dos dados citados nesta página
How to read this page
How to read the numbers here
Every value on "Science trivia questions and answers" comes from the source named beside its section, never from an estimate of our own with no origin.
Where the data comes from
Each section of "Science trivia questions and answers" names its official source; the verification date sits at the top of the page.
Linked to the rest of the module
"Science trivia questions and answers" is one of this module’s reference pages; the glossary below defines the technical terms used here.
More about “Science trivia questions and answers”
How many answers our own code checks
Of 10 questions on "Science trivia questions and answers", 4 have their answer tied to a value in one of our own datasets, checked automatically by our tests. The rest name their source alongside, for you to verify yourself.
Words on this page
Atomic number
The number of protons in an atom’s nucleus, written Z. It is this number, not the mass, that defines which element an atom is: every atom with 8 protons is oxygen, whether it has 8 or 18 neutrons.
Standard definition by IUPAC · Atomic number
Atomic weight
The average weight of an element’s atoms, weighted by how abundant each isotope is in nature, in atomic mass units. For 14 elements CIAAW publishes a range instead of a single value, because that abundance varies a little from sample to sample.
Standard definition by CIAAW — Commission on Isotopic Abundances and Atomic Weights · Atomic weight
Isotope
Atoms of the same element (same number of protons) with a different number of neutrons, and therefore a different mass. Carbon-12 and carbon-14 are isotopes of carbon; only the second one is radioactive.
Mole
The SI counting unit for atoms, molecules or other entities: one mole is exactly 6.02214076 × 10²³ of them, by the definition fixed in 2019. It is what ties a mass in grams to a number of particles.
Standard definition by BIPM — Bureau International des Poids et Mesures (SI) · Mole
Astronomical unit
The solar system’s reference distance, fixed at exactly 149,597,870,700 metres since 2012, close to the average Earth–Sun distance. It saves writing every planet’s orbit in kilometres with ten digits.
Standard definition by IAU — International Astronomical Union · Astronomical unit
Exoplanet
A planet orbiting a star other than the Sun. Most were found indirectly, by the star’s faint dimming as the planet crosses in front of it (transit) or by the gravitational wobble it causes in the star (radial velocity), not by direct image.
Standard definition by NASA Exoplanet Archive · Exoplanet