Science for grades 9–10: questions with answers
The Science questions for grades 9–10 from the game, with the correct answers and an explanation for each.
What is the approximate speed of light in a vacuum?
- 3,000 km/s
- 30,000 km/s
- 300,000 km/s
- 3,000,000 km/s
Correct answer: 300,000 km/s — Light travels at 299,792 km per second — around the Earth seven times in one second. Nothing with mass can reach that speed.
Which chemical symbol stands for potassium?
- K
- P
- Pt
- Po
Correct answer: K — K comes from kalium, the Latin name for potassium. Bananas are rich in it, and it is essential for nerves and muscles.
What are the unreactive gases in the last column of the periodic table called?
- Halogens
- Alkali metals
- Lanthanides
- Noble gases
Correct answer: Noble gases — Helium, neon, argon, krypton, xenon and radon have full outer electron shells, so they almost never form compounds. Neon's glow is used in signs.
How many pairs of chromosomes does a typical human cell contain?
- 21
- 23
- 46
- 48
Correct answer: 23 — Humans have 23 pairs, 46 chromosomes in all — one of each pair from each parent. Chimpanzees have 24 pairs.
Which is the closest star to the Sun?
- Sirius
- Betelgeuse
- Barnard's Star
- Proxima Centauri
Correct answer: Proxima Centauri — Proxima Centauri is about 4.2 light-years away — a spacecraft at today's speeds would need tens of thousands of years to reach it. It is too faint to see without a telescope.
Which astronomer published the heliocentric model of the Solar System in 1543?
- Ptolemy
- Tycho Brahe
- Galileo
- Copernicus
Correct answer: Copernicus — Copernicus's book placing the Sun at the centre appeared in the year of his death. Galileo defended the idea decades later and was tried for it.
Which number, approximately 2.718, is the base of natural logarithms?
- e
- i
- π
- φ
Correct answer: e — The number e appears wherever growth is continuous — compound interest, population growth, radioactive decay. It was named by Leonhard Euler.
What is the SI unit of electric charge?
- Coulomb
- Farad
- Tesla
- Weber
Correct answer: Coulomb — One coulomb is the charge carried by a current of one ampere in one second — about 6 billion billion electrons.
Which type of electromagnetic radiation has the highest frequency?
- Radio waves
- Infrared
- X-rays
- Gamma rays
Correct answer: Gamma rays — Gamma rays have the shortest wavelength and the most energy. They are produced in nuclear reactions and by the most violent events in space.
What is the process by which a cell divides into two identical cells?
- Mitosis
- Meiosis
- Osmosis
- Diffusion
Correct answer: Mitosis — Mitosis produces two identical copies for growth and repair. Meiosis, used to make sperm and egg cells, halves the number of chromosomes.
What is the atomic number of oxygen?
- 2
- 6
- 8
- 16
Correct answer: 8 — Oxygen has eight protons. Its most common form has eight neutrons too, giving it a mass number of 16.
What is the approximate age of the universe?
- 4.6 billion years
- 13.8 billion years
- 46 billion years
- 138 billion years
Correct answer: 13.8 billion years — The universe is about 13.8 billion years old, measured from the afterglow of the Big Bang. Earth, at 4.6 billion years, is a third of that age.
Which planet rotates almost on its side, tilted by about 98 degrees?
- Jupiter
- Saturn
- Uranus
- Neptune
Correct answer: Uranus — Uranus spins on its side, so each pole gets 42 years of sunlight followed by 42 years of darkness. A giant collision early in its history is the likely cause.
What is the approximate acceleration due to gravity at Earth's surface?
- 1 m/s²
- 9.8 m/s²
- 98 m/s²
- 980 m/s²
Correct answer: 9.8 m/s² — A falling object gains about 9.8 metres per second of speed every second. On the Moon the figure is roughly a sixth of that.
Which of these numbers is irrational?
- 0.5
- 2/3
- √2
- 4
Correct answer: √2 — An irrational number cannot be written as a fraction of two whole numbers. Legend says the Pythagoreans were shocked to discover √2 was one.
What is the largest artery in the human body?
- Aorta
- Vena cava
- Carotid
- Femoral
Correct answer: Aorta — The aorta leaves the heart and is about 2.5 cm wide. The vena cava is the largest vein, returning blood to the heart.
Who arranged the elements into the first widely accepted periodic table in 1869?
- Dalton
- Lavoisier
- Mendeleev
- Curie
Correct answer: Mendeleev — Mendeleev left gaps for elements not yet discovered and predicted their properties. Gallium and germanium were found within 20 years, just as he said.
Which trigonometric ratio is the opposite side divided by the hypotenuse?
- Sine
- Cosine
- Tangent
- Secant
Correct answer: Sine — Sine is opposite over hypotenuse, cosine is adjacent over hypotenuse, tangent is opposite over adjacent — remembered by many as SOH-CAH-TOA.
How many pairs of ribs does a typical human have?
- 10
- 12
- 14
- 16
Correct answer: 12 — Humans have 12 pairs of ribs, 24 in all — the same number in men and women. The lowest two pairs are 'floating' ribs, attached only at the spine.
What is the approximate value of the golden ratio?
- 1.41
- 1.62
- 2.72
- 3.14
Correct answer: 1.62 — The golden ratio, about 1.618, appears in the spirals of sunflower seeds and pine cones; consecutive Fibonacci numbers approach it.