Science for grades 7–8: questions with answers
The Science questions for grades 7–8 from the game, with the correct answers and an explanation for each.
What is the most abundant element in the universe?
- Helium
- Oxygen
- Hydrogen
- Carbon
Correct answer: Hydrogen — About three quarters of all ordinary matter in the universe is hydrogen, the simplest atom. Stars shine by fusing it into helium.
What is the atomic number of carbon?
- 2
- 4
- 6
- 8
Correct answer: 6 — The atomic number is the number of protons in the nucleus. Carbon's six protons let it form four bonds, the basis of all known life.
About how long does light from the Sun take to reach Earth?
- 8 minutes
- 8 hours
- 8 days
- 8 months
Correct answer: 8 minutes — Sunlight takes about 8 minutes and 20 seconds to cover the 150 million km to Earth. If the Sun vanished, we would not notice for eight minutes.
Which planet is closest in size to Earth?
- Mercury
- Mars
- Venus
- Neptune
Correct answer: Venus — Venus is about 95% of Earth's diameter and is often called Earth's twin. Mars is only about half Earth's diameter.
In which part of a plant cell does photosynthesis take place?
- Nucleus
- Mitochondrion
- Chloroplast
- Ribosome
Correct answer: Chloroplast — Chloroplasts contain chlorophyll, the green pigment that captures light. A single leaf cell can hold dozens of them.
Which organelle is often called the powerhouse of the cell?
- Nucleus
- Ribosome
- Golgi apparatus
- Mitochondrion
Correct answer: Mitochondrion — Mitochondria release energy from food. They have their own DNA, inherited only from the mother, which suggests they were once free-living bacteria.
What is the SI unit of energy?
- Watt
- Joule
- Newton
- Volt
Correct answer: Joule — One joule is about the energy needed to lift a small apple one metre. A food calorie is roughly 4,200 joules.
Which colour of visible light has the longest wavelength?
- Violet
- Green
- Yellow
- Red
Correct answer: Red — Red light has the longest wavelength and violet the shortest. Beyond red lies infrared, which we feel as heat but cannot see.
What is any non-zero number raised to the power of zero?
- 0
- 1
- The number itself
- Undefined
Correct answer: 1 — Any non-zero number to the power of zero equals 1. This keeps the rule that dividing powers subtracts exponents: 2³ ÷ 2³ = 2⁰ = 1.
How many degrees is each angle of an equilateral triangle?
- 30°
- 45°
- 60°
- 90°
Correct answer: 60° — The angles of a triangle sum to 180°, so three equal angles are 60° each. Six equilateral triangles fit together to form a hexagon.
Which large galaxy is the nearest neighbour of the Milky Way?
- Andromeda
- Triangulum
- Sombrero
- Whirlpool
Correct answer: Andromeda — Andromeda is about 2.5 million light-years away and visible to the naked eye. It is moving towards us and will merge with the Milky Way in about 4 billion years.
Which blood vessels carry blood away from the heart?
- Arteries
- Veins
- Capillaries
- Venules
Correct answer: Arteries — Arteries carry blood away from the heart under high pressure, which is why they have thick, muscular walls. Veins bring it back.
Which element has the chemical symbol Na?
- Nitrogen
- Neon
- Nickel
- Sodium
Correct answer: Sodium — Na comes from natrium, the Latin name for sodium. Pure sodium is a soft metal that reacts violently with water.
What is the chemical formula of methane?
- CH4
- C2H6
- CO2
- NH3
Correct answer: CH4 — Methane is the main component of natural gas and a powerful greenhouse gas. One carbon atom bonded to four hydrogen atoms makes it the simplest hydrocarbon.
What is the unit of electrical resistance?
- Volt
- Ampere
- Farad
- Ohm
Correct answer: Ohm — The ohm is named after Georg Ohm, whose law links voltage, current and resistance: V = I × R.
Which part of the brain controls balance and coordination?
- Cerebrum
- Cerebellum
- Brainstem
- Hypothalamus
Correct answer: Cerebellum — The cerebellum, at the back of the brain, is only a tenth of its volume but contains more than half of all its neurons.
Which planet has the Great Red Spot?
- Mars
- Jupiter
- Saturn
- Neptune
Correct answer: Jupiter — The Great Red Spot is a storm larger than Earth; it has been observed continuously since the 1830s and may be far older.
What is a polygon with ten sides called?
- Hexagon
- Decagon
- Nonagon
- Dodecagon
Correct answer: Decagon — The names come from Greek numbers: deca means ten, as in decade. A dodecagon has twelve sides.
What is the change in pitch of a passing siren called?
- Doppler effect
- Compton effect
- Photoelectric effect
- Hall effect
Correct answer: Doppler effect — Sound waves are squeezed together as a source approaches and stretched as it moves away. Astronomers use the same effect with light to measure how fast galaxies recede.
Which blood group is known as the universal donor?
- A
- B
- AB
- O
Correct answer: O — Group O red cells carry no A or B markers, so they can be given to almost anyone; O negative is the true universal donor. AB is the universal recipient.