The 10 quiz questions
Question 1 : How many planets does our solar system officially have?
Possible answers:
- 7
- 8
- 9
- 10
Explanation: Since 2006, the solar system has 8 planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Question 2 : What is the chemical formula for table salt?
Possible answers:
- CaCl
- MgCl
- NaCl
- KCl
Explanation: Sodium chloride (NaCl) is composed of one sodium atom (Na) and one chlorine atom (Cl). Salt was so precious in ancient times that Roman soldiers were sometimes paid in salt, hence the word "salary" (from Latin salarium).
Question 3 : What is the name of the force that attracts objects toward the center of the Earth?
Possible answers:
- Inertia
- Friction
- Gravity
- Pressure
Explanation: Gravity is the force of attraction that the Earth exerts on objects. Isaac Newton formalized it in 1687 after observing a falling apple.
Question 4 : What is the chemical symbol for water?
Possible answers:
- NaCl
- CO2
- O2
- H2O
Explanation: H2O means 2 hydrogen atoms and 1 oxygen atom. Surprising detail: these two highly reactive gases on their own (hydrogen is explosive, oxygen feeds fire) together form the most ordinary and most essential substance for life.
Question 5 : How many chromosomes do humans have?
Possible answers:
- 23
- 44
- 45
- 46
Explanation: Humans have 23 pairs of chromosomes, or 46 in total. Gametes (sperm and eggs) only have 23.
Question 6 : What is the largest organ in the human body?
Possible answers:
- The skin
- The brain
- The liver
- The lungs
Explanation: The skin weighs about 4 kg and covers 2 m² in an adult.
Question 7 : What is the speed of light in a vacuum?
Possible answers:
- 150,000 km/s
- 300,000 km/s
- 450,000 km/s
- 600,000 km/s
Explanation: Light travels at about 300,000 km/s (299,792,458 m/s exactly) in a vacuum. It is a fundamental constant of the universe, denoted "c".
Question 8 : What gas do we mainly breathe?
Possible answers:
- Hydrogen
- Helium
- Oxygen
- Nitrogen
Explanation: Air contains about 78% nitrogen and 21% oxygen. We say we breathe oxygen, but 4 out of 5 times each breath pulls in nitrogen, which comes back out unchanged: our body cannot metabolize it.
Question 9 : How many bones make up the adult human skeleton?
Possible answers:
- 186
- 206
- 226
- 246
Explanation: The adult skeleton has 206 bones. At birth, a baby has about 270, but many fuse together during growth.
Question 10 : How many chemical elements are officially listed in Mendeleev's periodic table in 2024?
Possible answers:
- 92
- 100
- 118
- 150
Explanation: The periodic table has 118 elements validated by IUPAC. The last one added, oganesson (118), was named in 2016 in honor of Russian physicist Yuri Oganessian.
