Iodine Trivia Questions and Answers

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  1. What is the atomic number of iodine?
    A: 50
    B: 52
    C: 53
    D: 55
    Correct Answer: C
    Explanation: Iodine’s atomic number is 53, indicating it has 53 protons in its nucleus.
  2. Who discovered iodine and in what year?
    A: Humphry Davy in 1813
    B: Joseph Louis Gay-Lussac in 1810
    C: Bernard Courtois in 1811
    D: Antoine Lavoisier in 1792
    Correct Answer: C
    Explanation: Bernard Courtois discovered iodine in 1811 while working with seaweed ash.
  3. What is iodine’s appearance in its solid form?
    A: Lustrous metallic gray
    B: Shiny yellow solid
    C: Dull black solid
    D: Greenish-yellow solid
    Correct Answer: A
    Explanation: Iodine’s solid form is described as a lustrous metallic gray solid.
  4. What color does iodine gas have?
    A: Green
    B: Blue
    C: Violet
    D: Orange
    Correct Answer: C
    Explanation: Iodine gas appears violet in color.
  5. What group in the periodic table does iodine belong to?
    A: Group 16
    B: Group 17
    C: Group 18
    D: Group 5
    Correct Answer: B
    Explanation: Iodine is part of Group 17 in the periodic table, which is the halogen group.
  6. What period in the periodic table does iodine occupy?
    A: Period 4
    B: Period 5
    C: Period 6
    D: Period 3
    Correct Answer: B
    Explanation: Iodine is located in Period 5 of the periodic table.
  7. What is the boiling point of iodine in Kelvin?
    A: 386.85 K
    B: 457.4 K
    C: 329.4 K
    D: 298.15 K
    Correct Answer: B
    Explanation: The boiling point of iodine is 457.4 Kelvin.
  8. What is iodine’s electronic configuration?
    A: [Kr] 5s2 4d10 5p5
    B: [Ar] 3d10 4s2 4p5
    C: [Xe] 6s2 4f14 5d10
    D: [Ne] 3s2 3p5
    Correct Answer: A
    Explanation: Iodine’s electronic configuration is [Kr] 4d10 5s2 5p5.
  9. What is the oxidation state of iodine in iodide (I−)?
    A: -2
    B: -1
    C: 0
    D: +1
    Correct Answer: B
    Explanation: In iodide (I−), iodine possesses an oxidation state of -1.
  10. What is the natural occurrence category of iodine?
    A: Synthetic
    B: Primordial
    C: Cosmogenic
    D: Transuranic
    Correct Answer: B
    Explanation: Iodine naturally occurs as a primordial element.
  11. Which country is a leading producer of iodine?
    A: Australia
    B: India
    C: Japan
    D: Canada
    Correct Answer: C
    Explanation: Japan is one of the leading producers of iodine.
  12. What chemical property makes iodine useful as a radiocontrast material?
    A: High atomic number
    B: High electronegativity
    C: Low melting point
    D: Low density
    Correct Answer: A
    Explanation: Iodine’s high atomic number makes it effective as a radiocontrast material because it enhances contrast in imaging.
  13. What is a significant historical use of iodine discovered by Casimir Davaine?
    A: Antiseptic action
    B: Food preservation
    C: Fuel additive
    D: Dye production
    Correct Answer: A
    Explanation: Casimir Davaine discovered the antiseptic action of iodine in 1873.
  14. Iodine is required for the synthesis of which type of body hormones?
    A: Adrenal hormones
    B: Thyroid hormones
    C: Growth hormones
    D: Insulin
    Correct Answer: B
    Explanation: Iodine is essential for the synthesis of thyroid hormones.
  15. What is the spectral form of iodine in its gas phase?
    A: Violet vapor
    B: Clear vapor
    C: Yellow vapor
    D: Red vapor
    Correct Answer: A
    Explanation: Iodine gas forms a violet vapor.
  16. What is the molecular formula for diatomic iodine?
    A: I
    B: I2
    C: I3
    D: I4
    Correct Answer: B
    Explanation: The molecular formula for diatomic iodine is I2.
  17. What is the primary decay mode of iodine-131?
    A: Alpha decay
    B: Beta decay
    C: Gamma decay
    D: Positron emission
    Correct Answer: B
    Explanation: Iodine-131 primarily undergoes beta decay.
  18. Which industrial process uses iodine as a catalyst?
    A: Haber process
    B: Cativa process
    C: Ostwald process
    D: Solvay process
    Correct Answer: B
    Explanation: Iodine is used as a catalyst in the industrial production of acetic acid through the Cativa process.
  19. Iodine has significant uptake specificity for what human body organ?
    A: Liver
    B: Kidneys
    C: Lungs
    D: Thyroid gland
    Correct Answer: D
    Explanation: Iodine is specifically taken up by the thyroid gland.
  20. What type of crystal structure does iodine have in its solid state?
    A: Simple cubic
    B: Face-centered cubic
    C: Base-centered orthorhombic
    D: Body-centered cubic
    Correct Answer: C
    Explanation: Solid iodine has a base-centered orthorhombic crystal structure.
  21. What is the Pauling scale electronegativity of iodine?
    A: 1.9
    B: 2.6
    C: 3.0
    D: 4.0
    Correct Answer: B
    Explanation: Iodine has a Pauling scale electronegativity of 2.66.
  22. What is the primary chemical reaction type iodine undergoes with metals?
    A: Reduction
    B: Oxidation
    C: Thermal decomposition
    D: Catalysis
    Correct Answer: B
    Explanation: Iodine typically undergoes oxidation reactions with metals.
  23. What is the melting point of iodine in Celsius?
    A: 256.7°C
    B: 113.7°C
    C: 99.56°C
    D: 0°C
    Correct Answer: B
    Explanation: Iodine melts at 113.7°C.
  24. What is the condition called that results from iodine deficiency?
    A: Rickets
    B: Goitre
    C: Scurvy
    D: Beriberi
    Correct Answer: B
    Explanation: Iodine deficiency can lead to the development of goitre.
  25. How many electron shells does iodine have?
    A: 2
    B: 4
    C: 5
    D: 7
    Correct Answer: C
    Explanation: Iodine has five electron shells (2, 8, 18, 18, 7).
  26. What is the common oxidation state of iodine in iodate (IO3−)?
    A: -1
    B: 0
    C: +5
    D: +3
    Correct Answer: C
    Explanation: In iodate (IO3−), iodine has an oxidation state of +5.
  27. Which halogen is immediately above iodine in the periodic table?
    A: Chlorine
    B: Bromine
    C: Astatine
    D: Fluorine
    Correct Answer: B
    Explanation: Bromine is located immediately above iodine in Group 17 of the periodic table.
  28. What is the density of iodine at room temperature in g/cm3?
    A: 1.94
    B: 2.44
    C: 4.94
    D: 7.24
    Correct Answer: C
    Explanation: The density of iodine at room temperature is 4.944 g/cm3.
  29. Which discovery assistant confirmed iodine as an element alongside Courtois?
    A: Antoine Lavoisier
    B: Joseph Louis Gay-Lussac
    C: Dmitri Mendeleev
    D: John Dalton
    Correct Answer: B
    Explanation: Joseph Louis Gay-Lussac confirmed iodine as an element after Bernard Courtois’ discovery.
  30. What phase is iodine in at standard temperature and pressure (STP)?
    A: Gas
    B: Liquid
    C: Plasma
    D: Solid
    Correct Answer: D
    Explanation: At standard temperature and pressure, iodine exists as a solid.
  31. What effect does iodine deficiency have on the brain development in infants?
    A: Causes hyperactivity
    B: Preventable intellectual disabilities
    C: Improves cognitive function
    D: Increases IQ
    Correct Answer: B
    Explanation: Iodine deficiency is the leading preventable cause of intellectual disabilities in infants.
  32. How does iodine exposure primarily occur in the workplace?
    A: Skin contact
    B: Eye contact
    C: Inhalation
    D: All of the above
    Correct Answer: D
    Explanation: Iodine exposure in the workplace can occur through skin contact, eye contact, inhalation, and ingestion.
  33. Iodine’s role in thyroid hormone production requires how many micrograms per day?
    A: 50 μg
    B: 70 μg
    C: 100 μg
    D: 200 μg
    Correct Answer: B
    Explanation: The thyroid gland needs about 70 μg of iodine per day to synthesize thyroid hormones.
  34. During what medical procedure can iodine be used to block the thyroid’s uptake of radioactive iodine?
    A: Detoxification
    B: Thyrotoxicosis treatment
    C: X-ray imaging
    D: Blood transfusion
    Correct Answer: B
    Explanation: Saturated potassium iodide is used to block thyroid uptake of radioactive iodine during thyrotoxicosis treatment.
  35. What is the half-life of iodine-131?
    A: 1 day
    B: 13 hours
    C: 59 days
    D: 8 days
    Correct Answer: D
    Explanation: Iodine-131 has a half-life of 8 days.
  36. Which solution of iodine is known to cause skin irritation with prolonged use?
    A: Lugol’s solution
    B: Tincture of iodine
    C: Betadine
    D: All of the above
    Correct Answer: D
    Explanation: Prolonged use of Lugol’s solution, tincture of iodine, and Betadine can cause skin irritation and tissue damage.
  37. What is a traditional iodine source no longer economically viable today?
    A: Seaweed
    B: Caliche
    C: Brine
    D: Salt mines
    Correct Answer: A
    Explanation: Kelp (seaweed) was an early source of iodine that is no longer economically viable.
  38. What technique uses iodine as a standard due to its range of sharp spectral lines?
    A: MRI
    B: Spectroscopy
    C: Ultrasound
    D: X-ray
    Correct Answer: B
    Explanation: Iodine is used as a standard in spectroscopy because of its sharp spectral lines in the 500-700 nm range.
  39. What color is iodine vapor when dissolved in nonpolar solvents?
    A: Yellow
    B: Green
    C: Violet
    D: Red
    Correct Answer: C
    Explanation: When iodine vapor is dissolved in nonpolar solvents, it appears violet.
  40. Which year did Gay-Lussac and Davy connect iodine with its Greek name ‘iodēs’ meaning ‘violet’?
    A: 1811
    B: 1812
    C: 1813
    D: 1814
    Correct Answer: D
    Explanation: It was in 1814 that Gay-Lussac and Davy connected iodine’s name to ‘iodēs’ due to its violet vapor.
  41. What is the Paul’s electronegativity scale of iodine?
    A: 2.23
    B: 2.66
    C: 2.80
    D: 3.16
    Correct Answer: B
    Explanation: Iodine has an electronegativity of 2.66 on the Pauling scale.
  42. In which form can iodine dissolve to form a triiodide ion?
    A: Solid iodine
    B: Iodine vapor
    C: Potassium iodide solution
    D: Hydroiodic acid
    Correct Answer: C
    Explanation: Iodine can dissolve in potassium iodide solution to form a triiodide ion.
  43. What is the highest oxidation state iodine can achieve in its compounds?
    A: +1
    B: +3
    C: +5
    D: +7
    Correct Answer: D
    Explanation: Iodine can achieve the highest oxidation state of +7 in its compounds.
  44. How many isotopes of iodine are known?
    A: 30
    B: 37
    C: 44
    D: 50
    Correct Answer: B
    Explanation: There are 37 known isotopes of iodine.
  45. Which radioisotope of iodine is useful in nuclear medicine imaging?
    A: Iodine-123
    B: Iodine-125
    C: Iodine-127
    D: Iodine-131
    Correct Answer: A
    Explanation: Iodine-123 is used in nuclear medicine imaging, including SPECT and CT scans.
  46. What is the empirical atomic radius of iodine?
    A: 120 pm
    B: 140 pm
    C: 160 pm
    D: 180 pm
    Correct Answer: B
    Explanation: Iodine’s empirical atomic radius is approximately 140 pm.
  47. In what form does iodine have a base-centered orthorhombic crystal structure?
    A: Liquid
    B: Gas
    C: Solid
    D: Plasma
    Correct Answer: C
    Explanation: Solid iodine has a base-centered orthorhombic crystal structure.
  48. What is the commonly used radiocontrast agent containing iodine?
    A: Barium sulfate
    B: Diatrizoic acid
    C: Gadolinium
    D: Perfluorooctanoic acid
    Correct Answer: B
    Explanation: Diatrizoic acid is an iodine-containing radiocontrast agent used in medical imaging.
  49. What is the primary reason iodine is added to salt?
    A: Flavor enhancement
    B: Prevent goitre
    C: Preserve freshness
    D: Improve texture
    Correct Answer: B
    Explanation: Iodine is added to salt primarily to prevent goitre linked to iodine deficiency.
  50. Which ion does iodine form when it dissolves in water?
    A: Iodide
    B: Iodate
    C: Triiodide
    D: Periodate
    Correct Answer: C
    Explanation: When iodine dissolves in water in the presence of iodide ions, it forms the triiodide ion (I3−).
  51. What breed of thyroid hormone contains 65% of iodine by molecular weight?
    A: T3
    B: T4
    C: T0a
    D: T1a
    Correct Answer: A
    Explanation: Triiodothyronine (T3) contains 65% of iodine by molecular weight.
  52. What element is required for the enzymatic production of T3 and T4 alongside iodine?
    A: Lithium
    B: Selenium
    C: Magnesium
    D: Zinc
    Correct Answer: B
    Explanation: Selenium is required for the enzymatic production of triiodothyronine (T3) and thyroxine (T4) alongside iodine.
  53. What color does iodine turn when tested with starch?
    A: Yellow
    B: Blue
    C: Green
    D: Red
    Correct Answer: B
    Explanation: When tested with starch, iodine turns blue, forming a starch-iodine complex.
  54. What is the common synthetic method for producing alkyl iodides?
    A: Grignard reagent reaction
    B: Hofmann rearrangement
    C: Williamson ether synthesis
    D: Finkelstein reaction
    Correct Answer: D
    Explanation: The Finkelstein reaction is a common method for producing alkyl iodides.
  55. Which ancient Greek word inspired the name for iodine?
    A: Ιώδης (iodēs)
    B: Χλωρός (chloros)
    C: Φθορός (phthoros)
    D: Βρωμίω (bromio)
    Correct Answer: A
    Explanation: The name for iodine was inspired by the ancient Greek word Ιώδης (iodēs), meaning “violet.”
  56. What is the role of iodine in spacecraft propulsion technology?
    A: Cooling agent
    B: Fuel source
    C: Ion thruster reaction mass
    D: Structural material
    Correct Answer: C
    Explanation: Iodine is used as the reaction mass in ion thruster propulsion systems for spacecraft.
  57. How does iodine disinfect wounds?
    A: By forming a barrier
    B: Through osmosis
    C: By releasing oxygen
    D: By its antiseptic action
    Correct Answer: D
    Explanation: Iodine disinfects wounds through its antiseptic action, killing pathogens.
  58. What process allows iodine to display semiconductor properties?
    A: Van der Waals bonding
    B: Thermal expansion
    C: Electronic interactions in crystalline layers
    D: Magnetic ordering
    Correct Answer: C
    Explanation: The semiconducting properties of iodine arise from significant electronic interactions in its crystalline layers.
  59. What is a common dietary supplement to provide iodine for livestock?
    A: Calcium iodide
    B: Sodium iodide
    C: Potassium iodide
    D: Ethylenediamine dihydroiodide
    Correct Answer: D
    Explanation: Ethylenediamine dihydroiodide (EDDI) is a common dietary iodine supplement for livestock.
  60. What is a significant environmental use for silver iodide?
    A: Pollution control
    B: Cloud seeding
    C: Soil stabilization
    D: Water purification
    Correct Answer: B
    Explanation: Silver iodide is used in cloud seeding to induce rain.

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