Science for grades 5–6: questions with answers
The Science questions for grades 5–6 from the game, with the correct answers and an explanation for each.
Which gas makes up about 78% of Earth's atmosphere?
- Nitrogen
- Oxygen
- Argon
- Carbon dioxide
Correct answer: Nitrogen — Nitrogen makes up about 78% of the air, oxygen 21% and argon almost 1%. Carbon dioxide is only about 0.04%.
A light-year is a unit of what?
- Distance
- Time
- Speed
- Brightness
Correct answer: Distance — A light-year is the distance light travels in one year — about 9.5 trillion km. The nearest star beyond the Sun is over four light-years away.
What is the hardest substance in the human body?
- Bone
- Enamel
- Cartilage
- Keratin
Correct answer: Enamel — Tooth enamel is harder than bone, but unlike bone it cannot repair itself once damaged.
How many bones are there in the adult human body?
- 176
- 196
- 206
- 226
Correct answer: 206 — Adults have 206 bones. Babies are born with about 270, many of which fuse together as they grow.
What is the chemical symbol for silver?
- Si
- Sr
- Ag
- Au
Correct answer: Ag — Ag comes from argentum, the Latin word for silver. Silver conducts electricity better than any other metal.
Which scientist formulated the three laws of motion?
- Galileo
- Kepler
- Einstein
- Newton
Correct answer: Newton — Isaac Newton published his laws of motion and law of gravity in the Principia in 1687, one of the most influential books in science.
What is the longest side of a right-angled triangle called?
- Adjacent
- Opposite
- Hypotenuse
- Bisector
Correct answer: Hypotenuse — The hypotenuse lies opposite the right angle. The word comes from Greek and means 'stretching under'.
Which is the hottest planet in the Solar System?
- Mercury
- Venus
- Earth
- Mars
Correct answer: Venus — Venus is about 465 °C at the surface — hotter than Mercury, though it is farther from the Sun, because its thick carbon dioxide atmosphere traps heat.
Which unit is used to measure frequency?
- Hertz
- Joule
- Tesla
- Pascal
Correct answer: Hertz — One hertz means one cycle per second. The unit is named after Heinrich Hertz, who first proved the existence of radio waves in the 1880s.
What is the largest bone in the human body?
- Femur
- Tibia
- Humerus
- Pelvis
Correct answer: Femur — The femur, or thigh bone, is the longest and strongest bone, about a quarter of a person's height. The smallest is the stapes in the ear.
What is the pH of pure water?
- 1
- 7
- 10
- 14
Correct answer: 7 — The pH scale runs from 0 to 14. Pure water is neutral at 7; lemon juice is about 2 and household bleach around 12.
What do the four angles of a quadrilateral add up to?
- 180°
- 270°
- 360°
- 540°
Correct answer: 360° — Any quadrilateral can be cut into two triangles, so its angles sum to twice 180 degrees.
How has Pluto been classified since 2006?
- Comet
- Asteroid
- Moon
- Dwarf planet
Correct answer: Dwarf planet — Pluto was demoted because it has not cleared its orbit of other objects. It is smaller than our Moon.
What kind of energy does a moving object have?
- Kinetic
- Potential
- Chemical
- Nuclear
Correct answer: Kinetic — Kinetic energy grows with the square of speed: a car going twice as fast has four times the kinetic energy, which is why braking distances grow so quickly.
Which organ produces the hormone insulin?
- Liver
- Kidney
- Spleen
- Pancreas
Correct answer: Pancreas — Insulin lets cells take up sugar from the blood. When the pancreas makes too little of it, the result is diabetes.
Which acid is found in the human stomach?
- Sulphuric acid
- Hydrochloric acid
- Nitric acid
- Citric acid
Correct answer: Hydrochloric acid — Stomach acid is strong enough to dissolve metal. A layer of mucus, renewed every few days, protects the stomach wall from digesting itself.
What is the distance around a circle called?
- Radius
- Diameter
- Chord
- Circumference
Correct answer: Circumference — The circumference is always about 3.14 times the diameter, whatever the size of the circle — that ratio is pi.
What does a barometer measure?
- Temperature
- Air pressure
- Precipitation
- Wind speed
Correct answer: Air pressure — Falling air pressure usually means rain is coming, which is why barometers were once found in most homes. The first one was built by Torricelli in 1643.
What is a space rock called once it has landed on Earth's surface?
- Meteor
- Meteoroid
- Asteroid
- Meteorite
Correct answer: Meteorite — A meteoroid is the rock in space, a meteor is the streak of light as it burns in the atmosphere, and a meteorite is what reaches the ground.
Whose theorem relates the three sides of a right-angled triangle?
- Euclid
- Archimedes
- Pythagoras
- Thales
Correct answer: Pythagoras — Pythagoras' theorem says the square on the hypotenuse equals the sum of the squares on the other two sides. Babylonians used it a thousand years before him.