Brain Night
Brain Night is the thinking person's round: science, maths, the human body, space, inventions and a few questions that look easy until you read them twice. You don't need a lab coat, just a clear head and a willingness to slow down for half a second. Below are 25 brain teaser and science trivia questions with answers, sorted from easy to hard.
Free, no sign-up needed. 20 questions, 10 seconds each.
Each question has four options. Make your choice, then tap "Show answer" for the answer, a short explanation and the source. Teachers use rounds like these as lesson starters, and they make a good family challenge at the kitchen table.
Want to keep going? The quick play deals 20 fresh Brain Night questions in the show's format: 5 easy, 10 medium, 4 hard and one Last Call. You get ten seconds per question, and faster right answers earn more points. Race the house crew, our badged AI opponents, or play on your own. Roxy Midnight hosts Brain Night on YouTube as well, and every night's exact 20 questions can be played here on the leaderboard.
Roxy's rule for trick questions: read the last word first. It's usually where the trap is hiding.
Pick your answer, then tap "Show answer". These questions never turn up in a night or a quick play.
1. Which scientist is famous for the laws of motion and universal gravitation?
Answer: A. Isaac Newton
Newton set out his laws of motion and universal gravitation in the Principia. They dominated physics for centuries until relativity superseded them.
2. Which gas do plants take in from the air to make food by photosynthesis?
Answer: B. Carbon dioxide
Photosynthetic plants build food from carbon dioxide and water using energy from light.
3. Which part of a cell is nicknamed its 'powerhouse'?
Answer: A. Mitochondrion
The nickname 'powerhouse of the cell' was popularised by Philip Siekevitz in 1957. Mitochondria release the energy that cells run on.
4. Which metal is liquid at normal room temperature?
Answer: B. Mercury
Mercury is the only metallic element known to be liquid at standard temperature and pressure. Bromine is the only other liquid element under those conditions.
5. How many chambers does the human heart have?
Answer: C. Four
The heart has two upper atria, which receive blood, and two lower ventricles, which pump it out.
6. Which blood cells carry oxygen around the body?
Answer: C. Red blood cells
Red blood cells are rich in hemoglobin, an iron-containing molecule that binds oxygen in the lungs and releases it in the tissues.
7. What is the name of the galaxy that contains our Solar System?
Answer: A. The Milky Way
The Milky Way is a barred spiral galaxy. Its name describes the hazy band of light we see from inside it.
8. Which planet's rusty orange-red colour earned it a famous nickname?
9. Roughly how fast does light travel through empty space?
Answer: B. 300,000 km per second
The speed of light in a vacuum is defined as exactly 299,792,458 metres per second, which is roughly 300,000 kilometres every second.
10. Which elementary particle is the quantum of light?
Answer: D. Photon
A photon is a quantum of the electromagnetic field and the force carrier for the electromagnetic force. Light and radio waves are made of photons.
11. Brass is an alloy of copper and which other metal?
Answer: C. Zinc
Brass is copper alloyed with zinc, typically about two-thirds copper. Bronze, by contrast, is mainly copper and tin.
12. What is the chemical symbol for sodium?
Answer: D. Na
Na comes from natrium, the Neo-Latin name for sodium, which refers to the Egyptian mineral natron. Berzelius published the symbol in 1814.
13. Which Russian chemist published a periodic table that predicted elements not yet discovered?
Answer: C. Dmitri Mendeleev
Mendeleev used his periodic law to predict the properties of germanium, gallium and scandium before any of them had been found.
14. Which animal is the only mammal capable of true, sustained flight?
Answer: D. Bat
Bats are the only mammals capable of sustained flight. Flying squirrels, colugos and sugar gliders merely glide.
15. Which microscopic animal is nicknamed the 'water bear'?
Answer: B. Tardigrade
Tardigrades are eight-legged micro-animals. Goeze first described them in 1773 as 'little water bears', a name inspired by their bear-like gait.
16. Which organ filters the blood to make urine?
Answer: C. Kidney
Filtration in the kidney's renal corpuscle keeps cells and large proteins in the blood while smaller materials are filtered out to eventually become urine.
17. Which vitamin does your skin make when it is exposed to sunlight?
Answer: B. Vitamin D
With enough UVB radiation from sunlight, the deeper layers of the skin's epidermis synthesise cholecalciferol, a form of vitamin D.
18. What is the medical name for the kneecap?
Answer: A. Patella
The patella is a flat, rounded triangular bone that covers and protects the front of the knee joint.
19. Who became the first person to travel into outer space?
Answer: B. Yuri Gagarin
Soviet cosmonaut Yuri Gagarin became the first person to journey into outer space during the first successful crewed spaceflight.
20. What was the name of the first artificial satellite to orbit Earth?
Answer: D. Sputnik 1
The Soviet Union launched Sputnik 1 on 4 October 1957. Its radio signals continued for 22 days until its batteries ran out.
21. Helium takes its name from the Greek word for what?
Answer: A. The Sun
Norman Lockyer named helium from helios, the Greek word for the Sun, because the element was first detected in sunlight.
22. Which element did Marie Curie name after her native country?
Answer: C. Polonium
Marie and Pierre Curie discovered polonium in July 1898, and named it after Poland, which was then partitioned between three empires.
23. Which Swedish naturalist formalised the modern system of naming species with two Latin names?
Answer: B. Carl Linnaeus
Linnaeus formalised binomial nomenclature, such as Homo sapiens. His 10th edition of Systema Naturae gave humans their full two-part name.
24. Which bone is the smallest in the human body?
Answer: C. Stapes
The stapes, named for its resemblance to a stirrup, is the third of the three tiny ossicles in the middle ear.
25. Which planet's axis lies almost flat, so it rolls around the Sun on its side?
Answer: D. Uranus
Uranus's axis of rotation is nearly parallel to the plane of the Solar System, giving it an axial tilt of about 98 degrees.
Quick play deals 20 fresh brain questions: 5 easy, 10 medium, 4 hard and a Last Call. Points for speed, and the house crew (badged AI regulars) will race you.