139 Science Quiz Questions & Answers

Below are 139 science quiz questions with the correct answer and a short explanation for each. Use them to revise, host a quiz night, or prepare for competitions — then challenge yourself with the timed, interactive version on QuizOxa.

Science Quiz Questions and Answers

1. Q1. What planet is called the Red Planet?

   ✅ Answer: Mars

   💡 Mars appears red due to iron oxide (rust) covering much of its surface.

2. Q2. What is H2O commonly known as?

   ✅ Answer: Water

   💡 H2O is the chemical formula for water, 2 hydrogen atoms bonded to 1 oxygen atom.

3. Q3. How many bones does the adult human body have?

   ✅ Answer: 206

   💡 The adult human body has 206 bones. Babies are born with around 270.

4. Q4. What is the closest star to Earth?

   ✅ Answer: The Sun

   💡 The Sun is the closest star to Earth at about 150 million kilometres away.

5. Q5. Which gas is most abundant in Earth's atmosphere?

   ✅ Answer: Nitrogen

   💡 Nitrogen makes up approximately 78% of Earth's atmosphere.

6. Q6. What organ pumps blood around the human body?

   ✅ Answer: Heart

   💡 The heart is a muscular organ that pumps blood continuously through the body.

7. Q7. What process do plants use to make food?

   ✅ Answer: Photosynthesis

   💡 Photosynthesis converts sunlight, water, and CO2 into glucose and oxygen.

8. Q8. What is the powerhouse of the cell?

   ✅ Answer: Mitochondria

   💡 Mitochondria produce ATP energy through cellular respiration.

9. Q9. What is the speed of light approximately?

   ✅ Answer: 300,000 km/s

   💡 Light travels at approximately 299,792 km/s in a vacuum.

10. Q10. What is the largest organ in the human body?

    ✅ Answer: Skin

    💡 Skin is the largest organ, covering about 2 square metres in adults.

11. Q11. Which planet is largest in our solar system?

    ✅ Answer: Jupiter

    💡 Jupiter is the largest planet, its mass is greater than all other planets combined.

12. Q12. What is the chemical symbol for gold?

    ✅ Answer: Au

    💡 Gold's chemical symbol Au comes from the Latin word 'Aurum'.

13. Q13. How long does light take to reach Earth from the Sun?

    ✅ Answer: 8 minutes

    💡 Sunlight takes approximately 8 minutes and 20 seconds to reach Earth.

14. Q14. What is the smallest unit of matter?

    ✅ Answer: Atom

    💡 An atom is the smallest unit of an element that retains its chemical properties.

15. Q15. How many chambers does the human heart have?

    ✅ Answer: 4

    💡 The human heart has 4 chambers: 2 atria and 2 ventricles.

16. Q16. What does DNA stand for?

    ✅ Answer: Deoxyribonucleic Acid

    💡 DNA stands for Deoxyribonucleic Acid, the molecule carrying genetic instructions.

17. Q17. Which planet has rings around it?

    ✅ Answer: Saturn

    💡 Saturn is famous for its stunning ring system made of ice and rock particles.

18. Q18. What is the freezing point of water in Celsius?

    ✅ Answer: 0°C

    💡 Water freezes at 0°C (32°F) at standard atmospheric pressure.

19. Q19. How many chromosomes do humans normally have?

    ✅ Answer: 46

    💡 Humans typically have 46 chromosomes, 23 pairs, in each cell.

20. Q20. What gas do humans exhale?

    ✅ Answer: Carbon Dioxide

    💡 Humans exhale carbon dioxide (CO2) as a byproduct of cellular respiration.

21. Q21. What is the hardest natural material on Earth?

    ✅ Answer: Diamond

    💡 Diamond is the hardest naturally occurring material, rated 10 on the Mohs hardness scale.

22. Q22. Which vitamin does sunlight provide to humans?

    ✅ Answer: Vitamin D

    💡 Exposure to sunlight triggers the skin to produce Vitamin D, essential for bone health.

23. Q23. What force keeps planets orbiting the Sun?

    ✅ Answer: Gravity

    💡 Gravity is the attractive force that keeps planets in orbit around the Sun.

24. Q24. What body organ filters blood and removes waste?

    ✅ Answer: Kidneys

    💡 The kidneys filter approximately 200 litres of blood daily, producing urine to remove waste.

25. Q25. How many planets are in our solar system?

    ✅ Answer: 8

    💡 There are 8 planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

26. Q26. What is the scientific study of earthquakes called?

    ✅ Answer: Seismology

    💡 Seismology is the scientific study of earthquakes and seismic waves.

27. Q27. What type of energy does the Sun primarily produce?

    ✅ Answer: Nuclear

    💡 The Sun produces nuclear fusion energy, converting hydrogen into helium.

28. Q28. What is the layer of Earth we live on called?

    ✅ Answer: Crust

    💡 The Earth's crust is the outermost solid layer on which we live.

29. Q29. Which blood type is known as the universal donor?

    ✅ Answer: O negative

    💡 O negative blood can be donated to anyone regardless of their blood type.

30. Q30. What is the study of plants called?

    ✅ Answer: Botany

    💡 Botany is the scientific study of plants.

31. Q31. What is the boiling point of water in Celsius?

    ✅ Answer: 100°C

    💡 Water boils at 100°C (212°F) at sea level under standard atmospheric pressure.

32. Q32. Which planet rotates on its side?

    ✅ Answer: Uranus

    💡 Uranus has a very unusual axial tilt of about 98 degrees, making it appear to rotate on its side.

33. Q33. What are the bones that protect the brain called?

    ✅ Answer: Skull

    💡 The skull is the bony structure that encases and protects the brain.

34. Q34. How many pairs of ribs does the human body have?

    ✅ Answer: 12

    💡 Humans have 12 pairs of ribs, 24 rib bones total.

35. Q35. What is the most common element in the universe?

    ✅ Answer: Hydrogen

    💡 Hydrogen is the most abundant element in the universe, making up about 75% of all normal matter.

36. Q36. What do we call animals that eat only plants?

    ✅ Answer: Herbivores

    💡 Herbivores are animals that feed exclusively on plants.

37. Q37. What is the study of the weather called?

    ✅ Answer: Meteorology

    💡 Meteorology is the scientific study of the atmosphere and weather patterns.

38. Q38. What is the longest bone in the human body?

    ✅ Answer: Femur

    💡 The femur (thigh bone) is the longest and strongest bone in the human body.

39. Q39. What percentage of Earth's surface is covered by water?

    ✅ Answer: 70%

    💡 Approximately 71% of Earth's surface is covered by water, mostly the oceans.

40. Q40. What layer around Earth blocks UV rays?

    ✅ Answer: Ozone Layer

    💡 The Ozone Layer in the stratosphere absorbs and blocks harmful ultraviolet radiation from the Sun.

41. Q41. What is a black hole?

    ✅ Answer: A region where gravity is so strong nothing can escape

    💡 A black hole is a region of spacetime with gravitational pull so strong that nothing — not even light — can escape.

42. Q42. How old is the universe estimated to be?

    ✅ Answer: 13.8 billion years

    💡 The universe is estimated to be 13.8 billion years old, determined by cosmic background radiation.

43. Q43. What is the largest moon in our solar system?

    ✅ Answer: Ganymede

    💡 Ganymede, a moon of Jupiter, is the largest moon in the solar system — even larger than the planet Mercury.

44. Q44. What is a light-year?

    ✅ Answer: The distance light travels in one year

    💡 A light-year is the distance light travels in one year — approximately 9.46 trillion km.

45. Q45. What is the Great Red Spot on Jupiter?

    ✅ Answer: A giant storm

    💡 The Great Red Spot is a massive, persistent anticyclonic storm on Jupiter, larger than Earth.

46. Q46. What is a nebula?

    ✅ Answer: A giant cloud of dust and gas in space

    💡 A nebula is a massive cloud of dust, hydrogen, helium, and plasma in space where stars are born.

47. Q47. What is a solar eclipse?

    ✅ Answer: Moon blocks the Sun

    💡 A solar eclipse occurs when the Moon passes between the Sun and Earth, briefly blocking sunlight.

48. Q48. How far is the Moon from Earth?

    ✅ Answer: 384,400 km

    💡 The Moon is approximately 384,400 km from Earth on average. Light takes about 1.28 seconds to travel this distance.

49. Q49. What is a pulsar?

    ✅ Answer: A rapidly rotating neutron star emitting beams of radiation

    💡 A pulsar is a highly magnetized, rapidly rotating neutron star that emits beams of electromagnetic radiation.

50. Q50. What will happen to our Sun in about 5 billion years?

    ✅ Answer: It will become a red giant, then a white dwarf

    💡 In about 5 billion years, the Sun will expand into a red giant engulfing Mercury and Venus, then shed its outer layers and become a white dwarf.

51. Q51. What is the process when a caterpillar becomes a butterfly?

    ✅ Answer: Metamorphosis

    💡 Metamorphosis is the biological process of transformation from larva to adult.

52. Q52. What organ produces insulin in the human body?

    ✅ Answer: Pancreas

    💡 The pancreas produces insulin, which regulates blood sugar levels.

53. Q53. What is the chemical formula for table salt?

    ✅ Answer: NaCl

    💡 Table salt is sodium chloride , chemical formula NaCl (sodium + chlorine).

54. Q54. Which is the fastest land animal?

    ✅ Answer: Cheetah

    💡 The cheetah is the fastest land animal, reaching speeds of up to 120 km/h.

55. Q55. What type of wave is visible light?

    ✅ Answer: Electromagnetic wave

    💡 Visible light is part of the electromagnetic spectrum.

56. Q56. How long does it take Earth to orbit the Sun?

    ✅ Answer: 365 days

    💡 Earth takes 365.25 days (one year) to complete one full orbit around the Sun.

57. Q57. What are the three states of matter?

    ✅ Answer: Solid, liquid, gas

    💡 The three common states of matter are solid, liquid, and gas.

58. Q58. What do red blood cells carry throughout the body?

    ✅ Answer: Oxygen

    💡 Red blood cells transport oxygen from the lungs to all cells throughout the body.

59. Q59. What is the scientific term for the Moon's shadow on Earth?

    ✅ Answer: Umbra

    💡 The Umbra is the darkest part of the Moon's shadow where a total solar eclipse is observed.

60. Q60. Which element has the chemical symbol Fe?

    ✅ Answer: Iron

    💡 Fe is the symbol for Iron, from the Latin word 'Ferrum'.

61. Q61. What is the most abundant gas in Earth’s atmosphere?

    ✅ Answer: Nitrogen

    💡 Nitrogen makes up about 78 percent of the air; oxygen is about 21 percent.

62. Q62. Which element has the atomic number 1?

    ✅ Answer: Hydrogen

    💡 Hydrogen is the lightest and most abundant element in the universe.

63. Q63. What is the chemical formula for table salt?

    ✅ Answer: NaCl

    💡 Table salt is sodium chloride, made of sodium and chlorine ions.

64. Q64. Who created the first widely recognised periodic table in 1869?

    ✅ Answer: Dmitri Mendeleev

    💡 Mendeleev left gaps for elements not yet discovered and predicted their properties.

65. Q65. What is the pH of pure water at 25°C?

    ✅ Answer: 7

    💡 A pH of 7 is neutral; lower values are acidic and higher values are alkaline.

66. Q66. Which element is a liquid metal at room temperature?

    ✅ Answer: Mercury

    💡 Mercury’s symbol, Hg, comes from the Greek hydrargyrum, meaning “liquid silver”.

67. Q67. What is the chemical symbol for iron?

    ✅ Answer: Fe

    💡 Fe comes from the Latin ferrum; Ir is iridium and I is iodine.

68. Q68. Which gas do plants absorb from the air for photosynthesis?

    ✅ Answer: Carbon dioxide

    💡 Plants use carbon dioxide, water and sunlight to make glucose and release oxygen.

69. Q69. What is the hardest natural substance?

    ✅ Answer: Diamond

    💡 Diamond, a form of pure carbon, scores 10 on the Mohs hardness scale.

70. Q70. Which group of the periodic table contains the noble gases?

    ✅ Answer: Group 18

    💡 Helium, neon, argon, krypton, xenon and radon are very unreactive because their outer electron shells are full.

72. Q71. What is the common name for sodium bicarbonate?

    ✅ Answer: Baking soda

    💡 Baking soda releases carbon dioxide when it reacts with acid, making cakes rise.

73. Q72. Marie Curie discovered two elements. One was radium; what was the other?

    ✅ Answer: Polonium

    💡 She named polonium after her home country, Poland.

74. Q73. What does the “O” stand for in H₂O?

    ✅ Answer: Oxygen

    💡 Each water molecule has two hydrogen atoms and one oxygen atom.

75. Q74. Which element makes up most of the Sun?

    ✅ Answer: Hydrogen

    💡 The Sun is about three-quarters hydrogen by mass, fused into helium in its core.

76. Q75. What type of bond forms when atoms share electrons?

    ✅ Answer: Covalent bond

    💡 Covalent bonds hold together molecules such as water and methane.

77. Q76. Which metal is the best conductor of electricity?

    ✅ Answer: Silver

    💡 Silver conducts best, but copper is used in wiring because it is far cheaper.

78. Q77. What is the chemical symbol for potassium?

    ✅ Answer: K

    💡 K comes from kalium, the Latin name; P is phosphorus.

79. Q78. What is rust chemically?

    ✅ Answer: Iron oxide

    💡 Rust forms when iron reacts with oxygen and water.

80. Q79. Which element has the chemical symbol Na?

    ✅ Answer: Sodium

    💡 Na comes from natrium, the Latin name for sodium.

81. Q80. What is the SI unit of force?

    ✅ Answer: Newton

    💡 One newton is the force that accelerates one kilogram by one metre per second squared.

82. Q81. Approximately how fast does light travel in a vacuum?

    ✅ Answer: 300,000 km per second

    💡 Light travels at about 299,792 km per second.

83. Q82. Who proposed the theory of general relativity?

    ✅ Answer: Albert Einstein

    💡 Einstein published general relativity in 1915, describing gravity as the curvature of spacetime.

84. Q83. Which of Newton’s laws states that every action has an equal and opposite reaction?

    ✅ Answer: Third law

    💡 The third law explains how rockets push themselves forward.

85. Q84. What is the SI unit of electrical resistance?

    ✅ Answer: Ohm

    💡 The ohm is named after German physicist Georg Ohm.

86. Q85. What does E = mc² relate?

    ✅ Answer: Energy and mass

    💡 Einstein’s equation shows a small amount of mass is equivalent to a huge amount of energy.

87. Q86. Sound cannot travel through which of these?

    ✅ Answer: A vacuum

    💡 Sound needs a medium to travel through, so space is silent.

88. Q87. What is the name for the bending of light as it passes from one material into another?

    ✅ Answer: Refraction

    💡 Refraction makes a straw look bent in a glass of water.

89. Q88. Which colour of visible light has the longest wavelength?

    ✅ Answer: Red

    💡 Red light has a wavelength of around 700 nanometres; violet is around 400.

90. Q89. What is the acceleration due to gravity at Earth’s surface, approximately?

    ✅ Answer: 9.8 m/s²

    💡 Objects falling freely near Earth gain about 9.8 metres per second of speed every second.

91. Q90. What is the SI unit of energy?

    ✅ Answer: Joule

    💡 The joule is named after James Prescott Joule; a watt is one joule per second.

92. Q91. Which particle carries a negative electric charge?

    ✅ Answer: Electron

    💡 Electrons orbit the nucleus, which contains positive protons and neutral neutrons.

93. Q92. At what temperature are the Celsius and Fahrenheit scales equal?

    ✅ Answer: −40 degrees

    💡 −40°C is exactly the same temperature as −40°F.

94. Q93. What is absolute zero on the Celsius scale, approximately?

    ✅ Answer: −273°C

    💡 Absolute zero is −273.15°C, or 0 kelvin, where particles have minimal motion.

95. Q94. Who discovered that white light is made of a spectrum of colours using a prism?

    ✅ Answer: Isaac Newton

    💡 Newton showed a prism splits white light and a second prism could recombine it.

96. Q95. What kind of energy does a stretched rubber band store?

    ✅ Answer: Elastic potential energy

    💡 The energy is released as kinetic energy when the band is let go.

97. Q96. What does a voltmeter measure?

    ✅ Answer: Potential difference

    💡 Voltage, or potential difference, is measured in volts.

98. Q97. Which scientist is known for the uncertainty principle?

    ✅ Answer: Werner Heisenberg

    💡 Heisenberg showed that position and momentum cannot both be known precisely at the same time.

99. Q98. What is the name for the speed needed to break free of a planet’s gravity without further propulsion?

    ✅ Answer: Escape velocity

    💡 Earth’s escape velocity is about 11.2 km per second.

100. Q99. Which type of electromagnetic radiation has the shortest wavelength?

     ✅ Answer: Gamma rays

     💡 Gamma rays have the shortest wavelengths and the highest energy.

101. Q100. What molecule carries genetic information in most living things?

     ✅ Answer: DNA

     💡 DNA (deoxyribonucleic acid) stores the instructions for building and running an organism.

102. Q101. Which scientists described the double-helix structure of DNA in 1953?

     ✅ Answer: Watson and Crick

     💡 James Watson and Francis Crick’s model relied on X-ray images by Rosalind Franklin.

103. Q102. What is the basic unit of life?

     ✅ Answer: Cell

     💡 All living things are made of one or more cells.

104. Q103. Who is known as the father of genetics for his experiments with pea plants?

     ✅ Answer: Gregor Mendel

     💡 Mendel’s 1860s experiments revealed how traits are inherited.

105. Q104. Which part of a plant cell carries out photosynthesis?

     ✅ Answer: Chloroplast

     💡 Chloroplasts contain chlorophyll, which captures energy from sunlight.

106. Q105. How many chromosomes does a typical human body cell contain?

     ✅ Answer: 46

     💡 Humans have 23 pairs of chromosomes, 46 in total.

107. Q106. Charles Darwin’s observations in which islands helped shape his theory of evolution?

     ✅ Answer: Galápagos Islands

     💡 Darwin noticed finches and tortoises varied from island to island.

108. Q107. What do we call an organism that makes its own food from sunlight?

     ✅ Answer: Producer

     💡 Producers such as plants and algae form the base of most food chains.

109. Q108. Which system of naming species uses two names, such as Homo sapiens?

     ✅ Answer: Binomial nomenclature

     💡 Carl Linnaeus popularised the system in the 18th century: genus first, then species.

110. Q109. What are proteins built from?

     ✅ Answer: Amino acids

     💡 Chains of amino acids fold into proteins, which do most of the work in cells.

111. Q110. What process do cells use to divide into two identical cells?

     ✅ Answer: Mitosis

     💡 Mitosis produces two genetically identical cells; meiosis produces sex cells.

112. Q111. Which kingdom do mushrooms belong to?

     ✅ Answer: Fungi

     💡 Fungi absorb nutrients from their surroundings rather than making food by photosynthesis.

113. Q112. What is the process by which water moves across a membrane from a dilute to a concentrated solution?

     ✅ Answer: Osmosis

     💡 Osmosis is why plant roots can draw water from the soil.

114. Q113. Who discovered penicillin in 1928?

     ✅ Answer: Alexander Fleming

     💡 Fleming noticed mould killing bacteria in a petri dish he had left out.

115. Q114. What is the name for the variety of life in a particular habitat or on Earth?

     ✅ Answer: Biodiversity

     💡 Biodiversity includes the variety of genes, species and ecosystems.

116. Q115. Which blood cells fight infection?

     ✅ Answer: White blood cells

     💡 White blood cells include several types that attack germs or make antibodies.

117. Q116. What is a close relationship between two species in which both benefit called?

     ✅ Answer: Mutualism

     💡 Bees and flowering plants are a classic example of mutualism.

118. Q117. Which organelle is called the “powerhouse of the cell”?

     ✅ Answer: Mitochondrion

     💡 Mitochondria release energy from food during respiration.

119. Q118. Edward Jenner developed the first vaccine, against which disease?

     ✅ Answer: Smallpox

     💡 Jenner used material from cowpox in 1796; smallpox was declared eradicated in 1980.

120. Q119. What are the four bases found in DNA?

     ✅ Answer: Adenine, thymine, guanine and cytosine

     💡 In RNA, uracil replaces thymine.

121. Q120. Who is credited with inventing the printing press with movable type in Europe around 1440?

     ✅ Answer: Johannes Gutenberg

     💡 Gutenberg’s press made books far cheaper and helped spread the Reformation and the Renaissance.

122. Q121. Who was awarded the first US patent for the telephone in 1876?

     ✅ Answer: Alexander Graham Bell

     💡 Bell’s patent was granted in March 1876, days before he spoke the first words over a telephone.

123. Q122. Who made the first controlled, powered aeroplane flight in 1903?

     ✅ Answer: The Wright brothers

     💡 Orville and Wilbur Wright flew at Kitty Hawk, North Carolina, on 17 December 1903.

124. Q123. Who invented the World Wide Web in 1989?

     ✅ Answer: Tim Berners-Lee

     💡 Berners-Lee proposed the web while working at CERN in Switzerland.

125. Q124. Which inventor developed a long-lasting practical incandescent light bulb in 1879?

     ✅ Answer: Thomas Edison

     💡 Edison and Britain’s Joseph Swan both developed bulbs and later merged their companies in the UK.

126. Q125. James Watt made major improvements to which machine?

     ✅ Answer: The steam engine

     💡 Watt’s separate condenser made steam engines far more efficient, powering the Industrial Revolution.

127. Q126. Who invented dynamite?

     ✅ Answer: Alfred Nobel

     💡 Nobel used his fortune to found the Nobel Prizes.

128. Q127. Who sent the first transatlantic radio signal in 1901?

     ✅ Answer: Guglielmo Marconi

     💡 Marconi received the signal in Newfoundland from a transmitter in Cornwall.

129. Q128. What did Karl Benz build in 1885–86, widely regarded as the first true automobile?

     ✅ Answer: A petrol-powered motor car

     💡 The Benz Patent-Motorwagen ran on a single-cylinder petrol engine.

130. Q129. Which ancient civilisation is credited with inventing paper, around the 2nd century AD?

     ✅ Answer: China

     💡 Cai Lun, a Han dynasty court official, is traditionally credited with improving papermaking.

131. Q130. Who invented the telegraph code of dots and dashes?

     ✅ Answer: Samuel Morse

     💡 Morse code was used from the 1840s and is still known by radio operators today.

132. Q131. Which Scottish engineer gave the first public demonstration of television in 1926?

     ✅ Answer: John Logie Baird

     💡 Baird demonstrated moving images to scientists in London in January 1926.

133. Q132. What did Wilhelm Röntgen discover in 1895?

     ✅ Answer: X-rays

     💡 Röntgen won the first Nobel Prize in Physics in 1901 for discovering X-rays.

134. Q133. Which company released the first iPhone in 2007?

     ✅ Answer: Apple

     💡 Steve Jobs introduced the iPhone in January 2007; it went on sale that June.

135. Q134. Nikola Tesla is best known for developing which kind of electrical system?

     ✅ Answer: Alternating current (AC)

     💡 AC won the “war of the currents” and powers most electricity grids today.

136. Q135. Who invented the first mechanical calculator able to add and subtract, the Pascaline?

     ✅ Answer: Blaise Pascal

     💡 Pascal built it in the 1640s to help his father, a tax collector.

137. Q136. Charles Babbage designed which early computing machine?

     ✅ Answer: The Analytical Engine

     💡 Ada Lovelace wrote what is often called the first computer program for Babbage’s Analytical Engine.

138. Q137. Who invented the cotton gin in 1793?

     ✅ Answer: Eli Whitney

     💡 The cotton gin quickly separated cotton fibres from seeds.

139. Q138. Which invention by Willis Carrier in 1902 changed how people live in hot climates?

     ✅ Answer: Modern air conditioning

     💡 Carrier designed it to control humidity at a printing plant.

140. Q139. Which device did Galileo improve and use in 1609–10 to discover Jupiter’s four largest moons?

     ✅ Answer: Telescope

     💡 Galileo’s observations supported the idea that not everything orbits Earth.

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