20 QUESTIONS · 5 FIELDS · ESTIMATION GAME · ABOUT 10 MINUTES

One drop of water holds more molecules than there are stars in the Milky Way.

Twenty questions on physics, chemistry, biology, Earth and space, and how science actually works, each explained. Then try to guess some of nature's numbers on a powers-of-ten scale. No sign-up, nothing saved.

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Stars in the Milky Way~1011
Water molecules in one drop~1021
Bar length on a powers-of-ten scale. On a normal scale, the stars bar would be invisible.
QUESTION 1 / 20 · PHYSICSEasy

What is the SI unit of force?

ROUND 1 OF 6 · 0 WITHIN ONE POWER OF TEN

Guess nature's numbers

Scientists often reason in powers of ten before working out exact figures. Each step on this slider multiplies by ten. Getting within one step of the real answer counts as a win.

How far is the Moon from Earth, in kilometres?
Your guess: 1.0 × 10¹²about 1.0 trillion
110⁶10¹²10¹⁸10²⁴

What this general science quiz covers, in short

Twenty multiple-choice questions, four in each of five areas: physics, chemistry, biology, Earth and space, and the scientific method. They cover the facts most people meet at school, plus how scientists test ideas.

The estimation game uses rounded, widely cited figures; some, like the number of cells in the body, are themselves estimates. The quiz is our own and not normed, so treat your score as a snapshot.

By What's Your IQ · Reviewed 4 Oct 2026
Format
20 multiple-choice questions, 4 options each
Fields
Physics, chemistry, biology, Earth and space, scientific method
Bonus
6-round powers-of-ten estimation game
Level
Roughly secondary-school science
Over 70%of researchers surveyed had failed to reproduce another scientist's experimentThat's why the scientific method stresses controls, repetition and peer review: a single result is a starting point, not a fact.1
1687Newton's Principia.Laws of motion and universal gravitation: one set of rules for falling apples and orbiting planets.
1859On the Origin of Species.Darwin set out evolution by natural selection, the unifying idea of biology.
1869The periodic table.Mendeleev arranged elements by properties and left gaps for ones not yet discovered, which were later found.
1953The double helix.Watson and Crick, using Rosalind Franklin's X-ray data, showed how DNA stores and copies genetic information.
  1. Baker, M. (2016). 1,500 scientists lift the lid on reproducibility. Nature, 533, 452–454.
  2. Watson, J. D., & Crick, F. H. C. (1953). Molecular structure of nucleic acids. Nature, 171, 737–738.

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