General Science: 110+ Most Important Numbers in Science

Question 1. How many pairs of chromosomes are contained in one typical human cell?
23 pairs (of chromosomes are contained in one typical human cell)
Note: There are 46 chromosomes, but 23 pairs. The question asked about pairs.

Question 2. What are the values (with units) that are associated with STP?
0°C and 1 atm (are the temperature and pressure associated with STP)
Note: This question didn’t specify whether or not to use SI units.

Question 3. What is the pH value for pure water? Which pH values can an acid or base have?
7 (is the pH value for pure water); an acid has a pH value below 7, while a base has a pH value above 7

Question 4. How much does a one-kilogram mass weigh in pounds near earth’s surface?
Approximately 2.2 pounds (is the weight of a 1-kg mass near earth’s surface)

Question 5. Approximately, how many days does it take for the moon to orbit the earth?
Approximately 29.5 days (relative to the sun, called a synodic month); we’ll also accept approximately 27.3 days (relative to the earth, called a sidereal month), since the question didn’t specify which; bonus for stating both

Question 6. What is the atomic number of carbon?
6 (is the atomic number of carbon)

Question 7. How many valence electrons does a neutral carbon atom have?
4 (is the number of valence electrons for a neutral carbon atom)
Note: The question didn’t ask for the “total” number of electrons (which is 6).

Question 8. What is the atomic mass of the isotope of carbon that has six neutrons?
12 amu, exactly (is the mass of the most abundant isotope of carbon, which has six neutrons in its nucleus); the masses of other elements are based on this value
Note: The question didn’t ask for the average atomic mass of carbon (12.01 amu), which is a weighted average of different isotopes; it specifically asked about carbon 12

Question 9. Roughly, how far away is the nearest star (other than the earth’s sun)?
About 4 light-years (is the distance to our sun’s nearest star); Proxima Centauri of the Alpha Centauri system is approximately 4.22 light-years from earth

Question 10. Approximately, how many different amino acids appear in the human genetic code?
Approximately 20 (kinds of amino acids are found in the human genetic code)

Question 11. Roughly, by what factor is the moon’s surface gravity weaker than earth’s surface gravity?
6 (the moon’s surface gravity is about 6 times weaker than earth’s)
Note: The question didn’t ask for the value (1.6 m/s2) of the moon’s surface gravity.

Question 12. How many elements on the periodic table are liquids at room temperature and pressure?
2 (bromine, Br, and mercury, Hg)

Question 13. Roughly, estimate the number of elements on the periodic table.
Roughly, 100; there are 118 confirmed as of 2019 (number of elements)

Question 14. At which temperature in degrees Celsius does water freeze?
0°C (is the freezing point of water in Celsius)

Question 15. At which temperature in degrees Celsius does water boil?
100°C (is the boiling point of water in Celsius)

Question 16. At which temperature in degrees Fahrenheit does water freeze?
32°F (is the freezing point of water in Fahrenheit)

Question 17. At which temperature in degrees Fahrenheit does water boil?
212°F (is the boiling point of water in Fahrenheit)

Question 18. Approximately, what is the value of pi?

3.14 (is the value of pi, to three significant figures); bonus for additional digits

Question 19. Approximately, what is Avogadro’s number?

6.02 × 1023 (is Avogadro’s number to three significant figures)

Question 20. Approximately, what is the speed of light in vacuum in SI units?

3.00 × 108 m/s (is the speed of light in vacuum to three significant figures)

Question 21. Approximately, what is Planck’s constant in SI units?

6.63 × 10–34 J·s (is Planck’s constant to three significant figures); for this value, the units could be Joules times seconds or they could be Joules per Hertz

Question 22. Approximately, what is gravitational acceleration near earth’s surface?

9.8 m/s2 (is earth’s surface gravity to two significant figures); note that a third digit is sensitive to a specific location on earth’s surface; 32 ft./s2 is also acceptable

Question 23. Approximately, what is the gravitational constant (in Newton’s law of gravity)?

6.67 × 10–11 N·m2/kg2 (is the value of the gravitational constant to three significant figures); this value is a universal constant, unlike the value from Question 22

Question 24. Approximately, what is the charge of an electron in SI units?
–1.60 × 10–19 C (is the charge of an electron to three significant figures)
Note: The negative sign is critical. Electrons have negative charge.

Question 25. Approximately, what is the mass of an electron in SI units?

9.11 × 10–31 kg (is the mass of an electron to three significant figures); one digit would be satisfactory

Question 26. Approximately, what is the value of the constant phi?

1.61 (is the value of phi, φ, to three significant figures); two digits will suffice; this value is known as the golden ratio

Question 27. Approximately, what is the density of water in SI units at standard temperature?
Approximately 1000 kg/m3 (is the density of pure water at standard temperature)
Note: 1 is incorrect because the question specified SI units (1 g/cm3 = 1000 kg/m3, which is a “fun” and instructive conversion)

Question 28. How many cells does one amoeba contain?
1 (is the number of cells contained in one amoeba; it is unicellular)

Question 29. Approximately, what percent of earth’s surface is covered with water?
Approximately 70% (of earth’s surface is covered with water); before you try to narrow it down further, you must decide whether you want to include fresh water and glaciers, for example

Question 30. Approximately, what percent of water is contained in the average adult human?
Approximately 60%, on average (of water is contained in an adult), if you account for all of the body parts; you also need to decide whether you wish to find the averages weighted by mass or weighted by volume; note that even the bones are significantly “watery,” though not nearly as much as most of the other organs

Question 31. Approximately, what percent of earth’s atmosphere contains oxygen?
Approximately 21%, on average (of earth’s atmosphere contains oxygen); however, it varies significantly for the different layers

Question 32. Approximately, what percent of earth’s atmosphere contains nitrogen?
Approximately 78%, on average (of earth’s atmosphere contains nitrogen); however, it varies significantly for the different layers

Question 33. Approximately, how many teeth does the typical human adult have?
30 (or more precisely, 32, is the number of teeth a typical human adult has)

Question 34. Roughly, estimate the number of bones in a typical adult human body.
200 (or more precisely, 206, is the number of bones in a typical adult human)

Question 35. How many pairs of ribs does the typical human adult have?
12 pairs (is the number of pairs of ribs in a typical adult human)
Note: There are 24 ribs, but 12 pairs. The question asked about pairs.

Question 36. Roughly, what is the size of a typical atom in SI units?
10–10 m (is the size of a typical atom); an Angstrom is not an SI unit; of course, it varies a bit, depending on the element

Question 37. Roughly, what is the size of a typical atomic nucleus in SI units?
10–15 m (is the size of a typical atomic nucleus); although a femtometer is not an SI unit, it does have a metric prefix combined with an SI unit (so we’ll give credit for 1 fm for this answer); again, it varies a bit, depending on the element

Question 38. Approximately, what is the surface temperature of the earth’s sun in Kelvin?
5800 K, on average (is the surface temperature of the sun); in Celsius it is about 5500°C, but the question specified Kelvin; it may vary over the surface; sunspots are significantly cooler

Question 39. Roughly, what is the age of the universe according to science?
14 billion years (is the age of the universe according to science); since it states “roughly,” we’ll accept anything from 10 to 20 billion (what’s a few billion years?)

Question 40. Roughly, what is the age of the earth’s sun according to science?

4.6 billion years (is the age of the earth’s sun according to science); we’ll accept anything from 4 to 5 billion (but if you said 10 billion, you may have been thinking of the sun’s lifetime; it has about 5 billion years left before it becomes a red giant)

Question 41. How many periods are shown on a standard periodic table?
7 (periods appear on a standard periodic table); be careful not to count the lanthanides and actinides that appear below the table (which are not separate periods, but are actually parts of periods 6 and 7)

Question 42. Which value in Celsius is considered to be room temperature?
We’ll accept anything from 20°C to 25°C (for the standard room temperature), though individual instructors or researchers may prefer a specific value

Question 43. What is the value of standard atmospheric pressure in Pascals?
101,325 Pascals (is standard atmospheric pressure); we’ll accept 100,000 Pa; note that the question specified Pascals (not atm or kPa, though we’ll accept 101 kPa)

Question 44. How many grams are there in one kilogram?
1000 (grams are in one kilogram: 1 kg = 1000 g)

Question 45. How many centimeters and how many millimeters are there in one meter?
100 cm and 1000 mm (are in one meter: 1 m = 100 cm, 1 m = 1000 mm)

Question 46. How many millimeters are there in one centimeter?
10 (millimeters are in one centimeter: 1 cm = 10 mm)

Question 47. How many cubic centimeters are there in one liter?
1000 (cubic centimeters are in one liter: 1 L = 1000 cc)

Question 48. How many square feet are there in one square yard?
9 (square feet are in one square yard); although there are 3 feet in 1 yard, with area it’s different: 1 yd.2 = (3 ft.)2 = 3 ft. × 3 ft. = 9 ft.2 (you can see this visually below)

Question 49. How many centimeters are there in one inch?

2.54 (centimeters are in one inch: 1 in. = 2.54 cm)

Question 50. How many bits are there in one byte?
8 (bits are in one byte: 1 byte = 8 bits)

Question 51. How many yards are there in one furlong?
220 (yards are in one furlong: 1 furlong = 220 yds.)

Question 52. How many US liquid pints are there in one gallon?
8 (US liquid pints are in one gallon: 1 gal. = 8 pt.)

Question 53. How many times louder is a 90-dB sound compared to a 50-dB sound?
10,000 times (is how much louder 90 dB is compared to 50 dB); same as 104

Question 54. How many significant figures are there in 0.00032100?
5 (significant figures are in 0.00032100); the significant figures are 32100; the leading zeroes don’t count, but the trailing zeroes do count

Question 55. How many moons orbit Mars?
2 (small moons orbit Mars: Phobos and Deimos)

Question 56. How many electrons can the d subshell hold?
10 (is how many electrons the d subshell can hold); the d subshell has 5 orbitals and each orbital can hold two electrons

Question 57. How many electrons can the f subshell hold?
14 (is how many electrons the f subshell can hold); the f subshell has 7 orbitals and each orbital can hold two electrons

Question 58. How many years does a sunspot cycle last, on average?
the best possible answer is 22 years, on average, but we’ll give credit for the popular answer of 11 years (for how long a sunspot cycle lasts); visually monitoring the sun, the pattern lasts an average of 11 years, but if instead you study the cycle knowing that it relates to the sun’s magnetic field, you would know that the polarity of the sun’s magnetic field reverses every 11 years, such that the 11-year period is actually one-half of the complete sunspot cycle (which is 22 years: 11 + 11 = 22)

Question 59. Approximately, what are the dates of the winter and summer solstices?
December 21 and June 21 (are the most common dates for the winter and summer solstices; they can vary by a day or two)
Why do the dates vary? Because the earth takes 365.24 days to complete its orbit, that 0.24 days can cause the date to change. Another complication is the extra day every four years (Leap Year) that helps to correct for that 0.24 days.

Question 60. Approximately, what are the dates of the vernal and autumnal equinoxes?
March 20 and September 23 (are the approximate dates of the vernal and autumnal equinoxes; they can vary by a day or two)
Why are the equinoxes and solstices sometimes on different dates of the month? Because the months don’t have exactly 31 days. For example, after June 21, both July and August have a 31st day before September. After December 21, February is a short month (usually 28 days, but occasionally 29).

Question 61. In which century did Benjamin Franklin live?
18th century (is when Benjamin Franklin lived; specifically, 1706–1790)

Question 62. In which century was Leonardo da Vinci born?
15th century (is when Leonardo da Vinci was born; specifically, 1452)

Question 63. In which year did man first walk on the moon?
1969 (is when Neil Armstrong walked on the moon; specifically, July 20)

Question 64. In which century was Galileo Galilei born?
16th century (is when Galileo Galilei was born; specifically, 1564)

Question 65. In which century did Archimedes live?
3rd century BC (is when Archimedes lived; specifically, 287 BC to 212 BC); the BC is critical (as opposed to AD)

Question 66. In which century was Isaac Newton born?
17th century (is when Isaac Newton was born; specifically, 1642)

Question 67. In which year were the first Nobel Prizes awarded?
1901 (is when the first Nobel Prizes were awarded)

Question 68. When was the American educational institution known as Harvard founded?
1636 (is when Harvard was founded, back in colonial times)

Question 69. Approximately, what is the speed of sound in air in SI units?
340 m/s, approximately (is the speed of sound in air at room temperature); the precise value depends on the pressure and temperature (not specified in the question); we’ll accept anything from 330 m/s to 350 m/s (but 760 mph is not in SI units)

Question 70. Approximately, what is the speed of an airplane in SI units if its speed is Mach 2?
680 m/s, approximately (is the speed of an airplane traveling Mach 2); if your answer is twice your answer to Question 69, you should receive credit

Question 71. Approximately, what values (in Kelvin and Pascal) form the triple point of water?
273 K and 600 Pa, approximately (form the triple point of H2O); more precisely, the triple point forms at 273.16 K and 611.7 Pa

Question 72. What is the spin of an electron?
½ (is the spin of an electron; if you want to be formal, multiply by ± h-bar)

Question 73. What is the spin of a photon?
1 (is the spin of a photon)

Question 74. Roughly, what is the heart rate of the average adult human while resting?
Roughly 60 to 100 beats per minute (is the average adult human heart rate); it’s about 1 beat per second

Question 75. How many vital organs does the human body have?
5 (organs of the human body are considered vital: the heart, brain, lungs, liver, and kidneys); perhaps you can make the case for more

Question 76. How many weeks is considered full-term for human pregnancy?
40 weeks (is considered full-term); we’ll accept 39 to 41

Question 77. What are the lengths of the small and large intestines of a typical human adult in meters?
About 6 to 7 m for the small intestines, 1.5 m for the large intestines, on average (though it can vary considerably); the adjectives “small” and “large” refer to diameter, not to length (as the small intestine is actually longer)

Question 78. What is the average reaction time for a typical adult human?
Roughly 0.15 s to 0.25 s (is the average adult reaction time); it also depends on the nature of the stimulus; we’ll accept as high as 0.3 s

Question 79. What is the near point of a typical, normal adult human eye?
25 cm (is the near point of the typical, normal adult human eye); if an object is closer than this distance, a typical eye can’t focus on it; this varies with age, too

Question 80. What is the normal body temperature of a typical adult human?
36° to 37°C or 97°F to 99°F (is the normal body temperature of a typical adult)

Question 81. How much money is awarded with each Nobel Prize?
That depends. In 1901, it was 150,000 SEK (Swedish Kronor). It has increased over time. In 2018, it was 9,000,000 SEK. The corresponding values in US dollars are about $20,000 in 1901 and $1.1 million in 2018 (for the value of a Nobel Prize). Currently, a good answer is roughly one million US dollars.

Question 82. What is the half-life of carbon-14?
Approximately 5700 years (is the half-life of carbon-14); we’ll take 5500 to 6000

Question 83. What is the ionization energy for the ground state of hydrogen in electron Volts?

13.6 eV (is the ionization energy for the ground state of hydrogen); we’ll accept 13 to 14 eV, and we’re not worried about the sign for this question

Question 84. What angle do the H–O–H atoms make in one H2O molecule?
105° (is the angle of the H–O–H bond in a polar H2O molecule); note that this is a little smaller than the 109° angle of a tetrahedron (do a little research if you’re interested in why); however, we’ll accept anything from 104° to 110°

Question 85. In the model of electron shells, which number comes after 2, 8, and 18?
32 (comes after 2, 8, and 18 in the electron shell model); it’s 2 times n2; these are the number of elements in the periods (rows) of the periodic table (2 in the first, 8 in the second and third, 18 in the fourth and fifth, 32 in the sixth and seventh)

Question 86. What are the horizontal and vertical components of a projectile’s acceleration?
0 and –9.81 m/s2 (are the horizontal and vertical components of the acceleration of a projectile, assuming it is launched near earth’s surface, that air resistance is negligible, neglecting earth’s rotation, and assuming a small change in altitude); the horizontal component of the acceleration is zero because a projectile’s horizontal component of velocity doesn’t change; vertically, there is gravitational acceleration pulling down, which changes the vertical component of velocity; we won’t penalize you for this minus sign as long as you “know” that it points downward

Question 87. What is the index of refraction for water?

1.3 (is the approximate index of refraction for water)

Question 88. What is the stellar classification of the earth’s sun (letter and number)?
G2 (is the stellar classification of the earth’s sun); bonus for G2V

Question 89. Roughly, what is the mass of the earth in SI units?
6 × 1024 kg (is the approximate mass of the earth); the kg (not g) is the SI unit; more precisely, it is 5.9 × 1024 kg, but we’ll accept 1024 to 1025 kg

Question 90. Roughly, what is the average radius of the earth in SI units?
6 × 106 m (is the approximate radius of the earth); the m (not km) is the SI unit; more precisely, it is 6.4 × 106 m, but we’ll accept 106 to 107 m

Question 91. Roughly, what is the average earth-moon distance in SI units?
4 × 108 m (is the approximate average earth-moon distance to one significant figure); more precisely, it is 3.8 × 108 m, but we’ll accept 108 to 109 m

Question 92. Approximately, how many times wider is the sun than the earth? Therefore, roughly how many earths could fit inside a volume equal to the volume of the sun?
100 (is approximately how many times wider the sun is compared to the earth); therefore, about 1,000,000 earths could fit inside of the volume of the sun
How? Because the volume of a sphere is So if R is 100 times larger, R3 is 1003 = 100×100×100 = 1,000,000 times larger; thus the volume is 1,000,000 times larger.

Question 93. Roughly, how much more dense is the earth (on average) than water?

5.5 times (is how much more dense the earth is on average compared to water); Saturn is actually less dense on average than water

Question 94. How many hydrogen atoms are present in a single glucose molecule?
12 (hydrogen atoms are in present in one molecule of C6H12O6)

Question 95. How many oxygen atoms are present in a single Al2(SO4)3 molecule?
12 (oxygen atoms are present in one “molecule” of Al2(SO4)3)

Question 96. Balance the reaction C6H14 + O2 —> CO2 + H2O.
2 C6H14 + 19 O2 —> 12 CO2 + 14 H2O (is the balanced reaction)

Question 97. Which finite temperature has the same numerical value in either Celsius or Fahrenheit?
–40° (is the same in both Celsius and Fahrenheit); you definitely need to include the minus sign; you can solve for this by setting TF equal to TC in TF = 9/5 TC + 32; as a check, you can see that 9/5 × (–40) + 32 = –72 + 32 = –40

Question 98. How many Joules of heat raise the temperature of 1 g of water from 14.5°C to 15.5°C?

4.186 J of heat (raises the temperature of 1 g of water from 14.5°C to 15.5°C); you should recognize this number either as the specific heat of water, 4186 J/kg/°C = 4.186 J/g/°C, or as the conversion from calories to Joules, 1 cal = 4.186 J, or from the explanation given in textbooks for the mechanical equivalent of heat; we’ll accept 4 J

Question 99. Roughly, when did the dinosaur extinction occur according to science?
About 65 to 70 million years ago (there was a mass extinction event affecting dinosaurs, according to science), associated with an impact in the Yucatán Peninsula

Question 100. How many dimensions of spacetime does superstring theory predict?
10 (dimensions of spacetime are predicted by superstring theory); we will accept 11 dimensions if you are thinking of M theory, or 9 dimensions for just space (not spacetime); if you said 26, you are thinking of bosonic string theory, whereas the question specified superstring theory

Question 101. Roughly, what is the wavelength of red light?
635 to 700 nm (is the approximate range of wavelengths for red light); we’ll accept 600 to somewhat over 700 nm; it’s equivalent to 6000 to 7000 Angstroms

Question 102. Roughly, what is the wavelength of violet light?
380 to 450 nm (is the approximate range of wavelengths for violet light); we’ll accept a specific value (rather than a range) for these two questions

Question 103. How many chambers are found in the stomach of a ruminant (such as a giraffe)?
4 (chambers are found in the stomach of a ruminant such as a giraffe)

Question 104. About how many genes on X and Y chromosomes carry instructions to make proteins?
Roughly 800 to 900 genes on the X chromosome and 50 to 70 genes on the Y chromosome (carry instructions to make proteins); we’ll allow a bit of flexibility

Question 105. Roughly, how many DNA base pairs does the human genome consist of?
Roughly 3,000,000,000 or 3 billion (DNA base pairs make up the human genome); we’ll accept 1 to 10 billion

Question 106. How many wings does a typical bee have?
4 (are how many wings a typical bee has)

Question 107. How many years can it take for the arctic woolly bear moth to fully develop?
About 14 to 15 years (is how long the arctic woolly bear caterpillar can take to reach its full adult moth form); we’ll accept anything from 8 to 16 years

Question 108. What fraction of nRT does the internal energy of a monatomic ideal gas equal?
3/2 (since U = 3/2 nRT for a monatomic ideal gas)

Question 109. What fraction of nRT does the internal energy of a diatomic ideal gas equal?
5/2 (since U = 5/2 nRT for a diatomic ideal gas)

Question 110. How long does one sidereal “day” last on Mercury?
Approximately 60 earth days (is how long one sidereal “day” lasts on Mercury, meaning one complete rotation on its axis); more precisely, it’s 58 to 59 days; don’t confuse this with one “year” on Mercury, which is 88 earth “days”

Question 111. How long does one sidereal “year” last on Neptune?
Approximately 165 earth years (is how long one sidereal “year” lasts on Neptune); we’ll accept 150 to 200 years

Question 112. How many generations of leptons and quarks are there?
3 (is how many generations of quarks and leptons have been discovered); the generations of quarks include up/down, charm/strange, and top/bottom; the three generations of leptons include the electron, muon, tau, and their neutrinos

Question 113. How does the charge of an up quark compare to the charge of a proton?
2/3 (is the charge of an up quark compared to the charge of a proton)

Question 114. How does the charge of a down quark compare to the charge of a proton?
–1/3 (is the charge of a down quark compared to the charge of a proton); the negative sign is critical

Question 115. Which Apollo spaceflight first resulted in astronauts walking on earth’s moon?
Apollo 11 (is the manned US spaceflight that landed on earth’s moon)

Question 116. Roughly, what is the height of the world’s tallest living tree in SI units?
Roughly 100 to 120 m (is the height of the world’s tallest living tree); it’s 116 meters, or 380 feet (in the California Redwood forest famous for giant sequoias)

Question 117. Roughly, how many neurons are found in a typical adult human brain?
Roughly 100 billion (neurons are in a typical adult human brain)