30 questions · true or false · Updated October 28, 2026
True or False Science Questions
The human body, space, physics and everyday chemistry are full of popular myths. These 30 true or false science questions bust them while you have fun, with a clear explanation for every answer. Bring them out at a party, for family time with teens or during a remote quiz.
Tip: read the statement out loud, let people buzz, then open the answer.
01We only use 10% of our brain.Show the answer
False
That’s a stubborn myth. Brain scans show that every area of the brain has a job, even if they aren’t all active at the same time.
02Sunlight takes about 8 minutes to reach us.Show the answer
True
It travels nearly 150 million km (93 million miles) in just over 8 minutes. So we always see the Sun as it was a few minutes earlier.
03Diamonds are made of carbon.Show the answer
True
Their carbon atoms are locked in a very tight network, making diamond one of the hardest natural materials. Graphite, also made of carbon, is very soft by contrast.
04Microwave ovens make food radioactive.Show the answer
False
Microwaves simply make the water molecules in food vibrate, which heats it up. They don’t make food radioactive.
05The blood in our veins is blue.Show the answer
False
Our blood is always red, darker or brighter depending on how much oxygen it carries. Veins look blue because of the way skin filters light.
06Venus is the hottest planet in the solar system.Show the answer
True
Its thick carbon dioxide atmosphere traps heat: it’s about 460 °C (860 °F) there, hotter than Mercury, even though Mercury is closer to the Sun.
07Lightning never strikes the same place twice.Show the answer
False
It often hits the same high points again and again. New York’s Empire State Building is struck around twenty times a year on average.
08Oxygen is the most abundant gas in the air we breathe.Show the answer
False
Air is about 78% nitrogen and 21% oxygen. Most of the rest is argon, plus a little carbon dioxide.
09The Sun alone holds more than 99% of the mass of the solar system.Show the answer
True
All the planets, moons, asteroids and comets combined weigh almost nothing next to it. Jupiter makes up most of what’s left.
10Sound can travel through the vacuum of space.Show the answer
False
Sound needs matter (air, water or a solid) to travel. In the vacuum of space, even an explosion would be completely silent.
11Ice floats because it is less dense than liquid water.Show the answer
True
Water expands as it freezes, so ice is lighter for the same volume. That’s unusual: most substances are denser as solids.
12The femur is the longest bone in the human body.Show the answer
True
This thigh bone is roughly a quarter of a person’s height. It’s also one of the strongest bones in the body.
13Summer is hotter because the Earth is closer to the Sun at that time of year.Show the answer
False
Seasons are caused by the tilt of Earth’s axis. In fact, the Earth is closest to the Sun in early January, in the middle of the Northern Hemisphere’s winter.
14The sound you hear when you hold a seashell to your ear is the sea.Show the answer
False
It’s the background noise around you, amplified and filtered by the shell’s hollow shape. You get the same effect with a cup or cupped hands.
15A shooting star is a star falling from the sky.Show the answer
False
It’s usually a speck of space dust, often no bigger than a grain of sand, burning up as it races through the atmosphere.
16A bolt of lightning is hotter than the surface of the Sun.Show the answer
True
Lightning can heat the air to nearly 30,000 °C (around 50,000 °F), roughly five times hotter than the Sun’s surface (about 5,500 °C).
17Seawater freezes at 0 °C (32 °F), just like fresh water.Show the answer
False
Salt lowers the freezing point: seawater freezes at around −2 °C (28 °F). That’s also why roads are salted in winter.
18Mixing vinegar and baking soda produces carbon dioxide.Show the answer
True
The acid in vinegar reacts with the baking soda and releases this gas, which makes the mixture fizz. It’s the secret behind classic science-fair “volcanoes”.
19Each taste is detected on its own specific zone of the tongue.Show the answer
False
The “tongue map” is a myth: receptors for sweet, salty, sour, bitter and umami are spread across the whole tongue.
20The skin is the largest organ of the human body.Show the answer
True
In an adult, it covers nearly 2 m² (about 20 sq ft) and weighs several pounds. It protects the body, helps control its temperature and senses touch.
21Table salt is mostly sodium chloride.Show the answer
True
Its chemical formula is NaCl: one sodium atom for every chlorine atom.
22Astronauts float on the International Space Station because there’s no gravity there.Show the answer
False
At that altitude, gravity is still about 90% as strong as on the ground. Astronauts float because they and the station are in constant free fall around the Earth.
23In a vacuum, a feather and a bowling ball fall at the same speed.Show the answer
True
With no air to slow them down, all objects fall the same way, whatever their mass. Astronauts demonstrated it on the Moon in 1971 with a hammer and a feather.
24Old windowpanes are thicker at the bottom because the glass has slowly flowed over the centuries.Show the answer
False
At room temperature, glass doesn’t flow measurably, even over centuries. The uneven thickness comes from old glassmaking methods, which produced irregular panes.
25The smallest bone in the human body is in the ear.Show the answer
True
It’s the stapes, or stirrup, in the middle ear. It’s about 3 mm (roughly a tenth of an inch) long and helps carry sound inward.
26We see lightning before we hear thunder because light travels faster than sound.Show the answer
True
Light arrives almost instantly, while sound travels about 340 meters (1,100 feet) per second. Counting the seconds in between gives you an idea of how far away the storm is: about 5 seconds per mile, or 3 per kilometer.
27Venus takes longer to spin once on its axis than to orbit the Sun.Show the answer
True
It takes about 243 Earth days to rotate once, but only about 225 days to complete its orbit. And it spins in the opposite direction to Earth!
28Jupiter is a rocky planet, like Earth.Show the answer
False
Jupiter is a gas giant, made mostly of hydrogen and helium. It’s also the largest planet in the solar system.
29Identical twins have different fingerprints.Show the answer
True
Even though they share the same DNA, their fingerprints form in a unique way in the womb, depending on each baby’s position and surroundings.
30The metal mercury is liquid at room temperature.Show the answer
True
It only freezes at around −39 °C (−38 °F). That’s why it was used in thermometers for so long.
Play these questions with the buzzer
In the same room, the host pulls these questions at random on the TV and everyone buzzes with their phone. Remotely, everyone can pick them on their turn in the group.
For an even livelier quiz, open the quiz buzzer: the players' phones turn into buzzers, right in the browser. You read the statement, the fastest player buzzes in and answers, then you read the explanation so everyone walks away a little smarter. Want to add your own questions? Our guide to writing good quiz questions helps you make them fair and easy to check.