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Friday, 9 October

JEE Main 2024 · ChemistryMultiple choiceSingle correctMediumRecall

JEE Main 9 April 2024, Shift 1, Chemistry Q67

Question 67 of 90 in this shift, Chemistry question 7 of 30, Section A.

The F−\mathrm{F^-} ions make the enamel on teeth much harder by converting hydroxyapatite (the enamel on the surface of teeth) into much harder fluoroapatite having the formula.
  1. (1)[3(Ca3(PO4)2)⋅Ca(OH)2][3(\mathrm{Ca_3(PO_4)_2})\cdot\mathrm{Ca(OH)_2}]
  2. (2)[3(Ca2(PO4)2)⋅Ca(OH)2][3(\mathrm{Ca_2(PO_4)_2})\cdot\mathrm{Ca(OH)_2}]
  3. (3)[3(Ca3(PO4)2)⋅CaF2][3(\mathrm{Ca_3(PO_4)_2})\cdot\mathrm{CaF_2}]Official answer
  4. (4)[3(Ca3(PO4)3)⋅CaF2][3(\mathrm{Ca_3(PO_4)_3})\cdot\mathrm{CaF_2}]

Official answer

Option 3

NTA final key.

Chapter
Environmental Chemistry
Topic
Environmental Chemistry
Idea tested
Drinking Water Standards: Fluoride Limits

Same topic in other shifts

All Environmental Chemistry questions
  1. 6 Apr 2023, Shift 1 · Q71The possibility of photochemical smog formation is more atEasySingle correct
  2. 8 Apr 2023, Shift 2 · Q70Which of these reactions is not a part of breakdown of ozone in stratosphere?MediumSingle correct
  3. 11 Apr 2023, Shift 1 · Q71Given below are two statements: Statement I: If BOD is 4 ppm and dissolved oxygen is 8 ppm, then it is a good quality water. Statement II:…MediumTwo statements
  4. 13 Apr 2023, Shift 2 · Q71Which of the following are the Green house gases? A. Water vapour B. Ozone C. I2\mathrm{I_2} D. Molecular hydrogen Choose the most…EasyOther
  5. 25 Jul 2022, Shift 1 · Q72The photochemical smog does not generally contain :EasySingle correct
  6. 28 Jul 2022, Shift 1 · Q71Given below are two statements : Statement I : In polluted water values of both dissolved oxygen and BOD are very low. Statement II :…EasyTwo statements

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.