Element 9: Fluorine (F) / āĻŽā§ŒāϞ ⧝: āĻĢā§āϞ⧁⧰āĻŋāύ (F) – Used in toothpaste, Teflon, refrigerants.


Basic Information / āĻŽā§ŒāϞāĻŋāĻ• āϤāĻĨā§āϝ



  • Name: Fluorine / āύāĻžāĻŽ: āĻĢā§āϞ⧁⧰āĻŋāύ

  • Symbol: F / āϚāĻŋāĻšā§āύ: F

  • Atomic Number: 9 / āĻĒāĻžā§°āĻŽāĻžāĻŖā§ąāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž: ⧝

  • Nature: Non-metal (Gas) / āĻĒā§ā§°āĻ•ā§ƒāϤāĻŋ: āĻ…āϧāĻžāϤ⧁ (āϗ⧇āĻ›)


Fluorine is the most reactive non-metal. : āĻĢā§āϞ⧁⧰āĻŋāύ āĻšā§ˆāϛ⧇ āφāϟāĻžāχāϤāĻ•ā§ˆ āϏāĻ•ā§ā§°āĻŋāϝāĻŧ āĻ…āϧāĻžāϤ⧁āĨ¤


Structure of Atom / āĻĒā§°āĻŽāĻžāϪ⧁⧰ āĻ—āĻ āύ



  • Protons: 9 / āĻĒā§ā§°ā§‹āϟāύ: ⧝

  • Electrons: 9 / āχāϞ⧇āĻ•ā§āĻŸā§ā§°āύ: ⧝

  • Neutrons: 10 (usually) / āύāĻŋāωāĻŸā§ā§°āύ: ā§§ā§Ļ (āϏāĻžāϧāĻžā§°āĻŖāϤ⧇)


Electronic configuration: 2, 7 : āχāϞ⧇āĻ•ā§āĻŸā§ā§°āύ āĻŦāĻŋāĻ¨ā§āϝāĻžāϏ: 2, 7


Properties / āϗ⧁āĻŖāϏāĻŽā§‚āĻš



  • Pale yellow gas / āĻšāĻžāϞāϧ⧀āϝāĻŧāĻž ā§°āς⧰ āϗ⧇āĻ›

  • Highly reactive / āĻŦāĻšā§āϤ āϏāĻ•ā§ā§°āĻŋāϝāĻŧ

  • Does not exist freely / āĻāϕ⧇āϞāϗ⧇ āĻĒā§‹ā§ąāĻž āύāĻžāϝāĻžāϝāĻŧ

  • Exists as F₂ molecule / F₂ āĻ…āϪ⧁ āĻšāĻŋāϚāĻžāĻĒ⧇ āĻĨāĻžāϕ⧇


Occurrence / āĻ•’āϤ āĻĒā§‹ā§ąāĻž āϝāĻžāϝāĻŧ



  • Found in compounds (fluorides)

  • Not found freely in nature : āĻĒā§ā§°āĻžāĻ•ā§ƒāϤāĻŋāĻ• āĻ…ā§ąāĻ¸ā§āĻĨāĻžāϤ āĻāϕ⧇āϞāϗ⧇ āύāĻžāĻĨāĻžāϕ⧇āĨ¤


Uses / āĻŦā§āĻ¯ā§ąāĻšāĻžā§°



  • Toothpaste (fluoride) / āĻĻāĻžāρāϤ⧰ āĻĒ⧇āĻˇā§āϟāϤ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻšāϝāĻŧ

  • Chemicals / ā§°āĻžāϏāĻžāϝāĻŧāύāĻŋāĻ• āĻĒāĻĻāĻžā§°ā§āĻĨ āϤ⧈āϝāĻŧāĻžā§°āϤ

  • Protects teeth / āĻĻāĻžāρāϤ ā§°āĻ•ā§āώāĻž āϕ⧰⧇


Importance / āϗ⧁⧰⧁āĻ¤ā§āĻŦ



  • Prevents tooth decay / āĻĻāĻžāρāϤ⧰ āĻ•ā§āώāϝāĻŧ ā§°ā§‹āϧ āϕ⧰⧇

  • Used in industrial chemicals

  • Important in chemical reactions


Why is Fluorine So Reactive ? / āĻ•āĻŋāϝāĻŧ āĻĢā§āϞ⧁⧰āĻŋāύ āĻŦāĻšā§āϤ āϏāĻ•ā§ā§°āĻŋāϝāĻŧ ?



  • It needs 1 electron to complete its outer shell. : āχāϝāĻŧāĻžāĻ• āĻŦāĻžāĻšā§āϝāĻŋāĻ• āĻ–ā§‹āϞ āĻĒā§‚ā§°āĻŖ āϕ⧰āĻŋāĻŦāϞ⧈ ā§§āϟāĻž āχāϞ⧇āĻ•ā§āĻŸā§ā§°āύ āϞāĻžāϗ⧇āĨ¤

  • So it reacts very quickly. : āϏ⧇āϝāĻŧ⧇ āχ āĻ¤ā§ŽāĻ•ā§āώāĻŖāĻžāϤ āĻŦāĻŋāĻ•ā§ā§°āĻŋāϝāĻŧāĻž āϕ⧰⧇āĨ¤


Fact / āϤāĻĨā§āϝ : Fluoride helps prevent tooth decay. : āĻĢā§āϞ⧁⧰āĻžāχāĻĄā§‡ āĻĻāĻžāρāϤ⧰ āĻ•ā§āώāϝāĻŧ ā§°ā§‹āϧ āϕ⧰⧇āĨ¤


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Fluorine (F) – PYQ MCQs


Q1. Fluorine belongs to which group of the periodic table ? :  āĻĢā§āϞ⧁⧰āĻŋāύ āĻ†ā§ąā§°ā§āϤ āϏāĻžā§°āϪ⧀⧰ āϕ⧋āύāĻŸā§‹ āĻ—ā§‹āϟāϤ āĻĒ⧰⧇ ?
(a) Group 16 (b) Group 17 (c) Group 18 (d) Group 15


Ans: (b) Group 17
Explanation: Fluorine is a halogen, placed in Group 17. : āĻĢā§āϞ⧁⧰āĻŋāύ āĻāϟāĻž āĻšā§‡āϞ’āĻœā§‡āύ, āϏ⧇āϝāĻŧ⧇ āĻ—ā§‹āϟ ā§§ā§­āϤ āĻĨāĻžāϕ⧇āĨ¤


Q2. Atomic number of fluorine is: āĻĢā§āϞ⧁⧰āĻŋāύ⧰ āĻĒāĻžā§°āĻŽāĻžāĻŖā§ąāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž āĻ•āĻŋ ?
(a) 7 (b) 8 (c) 9 (d) 10


Ans: (c) 9
Explanation: Atomic number = number of protons = 9. : āĻĒāĻžā§°āĻŽāĻžāĻŖā§ąāĻŋāĻ• āϏāĻ‚āĻ–ā§āϝāĻž = āĻĒā§ā§°ā§‹āϟāύ⧰ āϏāĻ‚āĻ–ā§āϝāĻž = ⧝āĨ¤


Q3. Fluorine is classified as: āĻĢā§āϞ⧁⧰āĻŋāύāĻ• āϕ⧇āύ⧇āĻ•ā§ˆ āĻļā§ā§°ā§‡āĻŖā§€āĻŦāĻĻā§āϧ āϕ⧰āĻž āĻšāϝāĻŧ ?
(a) Metal (b) Non-metal (c) Metalloid (d) Noble gas


Ans: (b) Non-metal
Explanation: Fluorine is a non-metal gas. : āĻĢā§āϞ⧁⧰āĻŋāύ āĻāϟāĻž āĻ…āϧāĻžāϤ⧁ āϗ⧇āĻ›āĨ¤


Q4. Fluorine is the ______ non-metal. : āĻĢā§āϞ⧁⧰āĻŋāύ āĻšā§ˆāϛ⧇ ______ āĻ…āϧāĻžāϤ⧁āĨ¤
(a) Least reactive (b) Most reactive (c) Heaviest (d) Softest


Ans: (b) Most reactive
Explanation: Fluorine is the most reactive non-metal. : āĻĢā§āϞ⧁⧰āĻŋāύ āφāϟāĻžāχāϤāĻ•ā§ˆ āϏāĻ•ā§ā§°āĻŋāϝāĻŧ āĻ…āϧāĻžāϤ⧁āĨ¤


Q5. Fluorine exists as: āĻĢā§āϞ⧁⧰āĻŋāύ āϕ⧇āύ⧇āĻ•ā§ˆ āĻĨāĻžāϕ⧇ ?
(a) F (b) F₂ (c) F₃ (d) HF


Ans: (b) F₂
Explanation: Fluorine exists as a diatomic molecule. : āĻĻ⧁āϟāĻž āĻĒā§°āĻŽāĻžāϪ⧁⧰⧇ āĻ—āĻ āĻŋāϤ (F₂)āĨ¤


Q6. Fluorine is used in: āĻĢā§āϞ⧁⧰āĻŋāύ āĻ•’āϤ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻšāϝāĻŧ ?
(a) Glass (b) Toothpaste (c) Wood (d) Cement


Ans: (b) Toothpaste
Explanation: Fluoride compounds are used in toothpaste. : āĻĻāĻžāρāϤ⧰ āĻĒ⧇āĻˇā§āϟāϤ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻšāϝāĻŧāĨ¤


Q7. Fluorine does not exist freely because: āĻĢā§āϞ⧁⧰āĻŋāύ āĻāϕ⧇āϞāϗ⧇ āύāĻžāĻĨāĻžāϕ⧇ āĻ•āĻžā§°āĻŖ -
(a) It is heavy (b) It is very reactive (c) It is solid (d) It is metal


Ans: (b) It is very reactive
Explanation: It reacts quickly with other elements. : āχ āĻŦāĻšā§āϤ āĻĻā§ā§°ā§āϤ āĻŦāĻŋāĻ•ā§ā§°āĻŋāϝāĻŧāĻž āϕ⧰⧇āĨ¤


Q8. Number of electrons in fluorine atom is: āĻĢā§āϞ⧁⧰āĻŋāύ āĻĒā§°āĻŽāĻžāϪ⧁āϤ āĻ•āĻŋāĻŽāĻžāύ āχāϞ⧇āĻ•ā§āĻŸā§ā§°āύ āĻĨāĻžāϕ⧇ ?
(a) 7 (b) 8 (c) 9 (d) 10


Ans: (c) 9
Explanation: Electrons = atomic number = 9. : āχāϞ⧇āĻ•ā§āĻŸā§ā§°āύ = ⧝āĨ¤


Q9. Fluoride helps to: āĻĢā§āϞ⧁⧰āĻžāχāĻĄā§‡ āĻ•āĻŋ āϏāĻšāĻžāϝāĻŧ āϕ⧰⧇ ?
(a) Increase weight (b) Prevent tooth decay (c) Burn faster (d) Make metal


Ans: (b) Prevent tooth decay
Explanation: Fluoride protects teeth from decay. : āĻĻāĻžāρāϤ⧰ āĻ•ā§āώāϝāĻŧ ā§°ā§‹āϧ āϕ⧰⧇āĨ¤


Q10. Fluorine is: āĻĢā§āϞ⧁⧰āĻŋāύ āĻšā§ˆāϛ⧇ -
(a) Hard solid (b) Liquid metal (c) Pale yellow gas (d) Black solid


Ans: (c) Pale yellow gas


Explanation: Fluorine is a pale yellow gas. : āĻĢā§āϞ⧁⧰āĻŋāύ āĻšāĻžāϞāϧ⧀āϝāĻŧāĻž ā§°āϙ⧰ āϗ⧇āĻ›āĨ¤